JP2021007158A - Transistor manufacturing method - Google Patents

Abstract

To impart a stable electric property to a semiconductor device arranged by use of an oxide semiconductor, thereby providing a highly reliable semiconductor device.SOLUTION: In a process for manufacturing a transistor including an oxide semiconductor film, an oxygen doping treatment on an oxide semiconductor film is performed, and then a thermal treatment on the oxide semiconductor film and an aluminum oxide film provided over the oxide semiconductor film is performed to form an oxide semiconductor film having a region containing oxygen of a quantity over a stoichiometric composition ratio. The transistor with the oxide semiconductor film is reduced in the change of a transistor threshold voltage before and after a bias-thermal stress test (BT test), and it can be made a highly reliable transistor.SELECTED DRAWING: Figure 1

Description

The present invention relates to a semiconductor device and a method for manufacturing the semiconductor device.

In the present specification, the semiconductor device refers to all devices that can function by utilizing the semiconductor characteristics, and the electro-optical device, the semiconductor circuit, and the electronic device are all semiconductor devices.

Attention is being paid to a technique for constructing a transistor by using a semiconductor thin film formed on a substrate having an insulating surface. The transistor is widely applied to electronic devices such as integrated circuits (ICs) and image display devices (display devices). Silicon-based semiconductor materials are widely known as semiconductor thin films applicable to transistors, but oxide semiconductors are attracting attention as other materials.

For example, a transistor using an amorphous oxide containing indium (In), gallium (Ga), and zinc (Zn) having an electron carrier concentration of less than 10 ¹⁸ / cm ³ is disclosed as the active layer of the transistor. (See Patent Document 1).

Japanese Unexamined Patent Publication No. 2006-165528

However, in a semiconductor device having an oxide semiconductor, if the oxide semiconductor has an oxygen deficiency, its electric conductivity may change. Such a phenomenon becomes a factor of fluctuation in electrical characteristics for a transistor using an oxide semiconductor.

In view of such a problem, one of the purposes of the present invention is to provide a semiconductor device using an oxide semiconductor with stable electrical characteristics and to provide a highly reliable semiconductor device.

In the process of manufacturing a transistor containing an oxide semiconductor film, the oxide semiconductor film is oxygen-doped, and then the oxide semiconductor film and the aluminum oxide film provided on the oxide semiconductor film are heat-treated. , Form an oxide semiconductor film having a region containing oxygen exceeding the chemical quantitative composition ratio. It is also possible to remove impurities containing hydrogen atoms by heat-treating the oxide semiconductor film. More specifically, for example, the following production method can be used.

One aspect of the present invention includes a step of forming a silicon oxide film, a step of forming an oxide semiconductor film in contact with the silicon oxide film, a step of forming an aluminum oxide film on the oxide semiconductor film, and an oxide semiconductor film. Is oxygen-doped and oxygen is supplied to the oxide semiconductor film to form a region having more oxygen than the chemical quantitative composition ratio in the oxide semiconductor film, and the oxygen-supplied oxide semiconductor film and aluminum oxide. It is a method for manufacturing a semiconductor device including a step of heat-treating a film.

Further, in another aspect of the present invention, a step of forming a silicon oxide film, a step of forming an oxide semiconductor film in contact with the silicon oxide film, and a first heat treatment of the oxide semiconductor film are performed to obtain an oxide. The process of removing hydrogen atoms in the semiconductor film and the oxygen doping treatment of the oxide semiconductor film to supply oxygen to the oxide semiconductor film to create a region where the oxide semiconductor film has more oxygen than the chemical quantitative composition ratio. This is a method for manufacturing a semiconductor device, which includes a step of forming and a step of forming an aluminum oxide film on an oxide semiconductor film and performing a second heat treatment.

Further, in the above method for manufacturing a semiconductor device, it is preferable to continuously form an oxide semiconductor film without releasing it to the atmosphere after forming a silicon oxide film.

Further, in the above method for manufacturing a semiconductor device, it is preferable that the peak oxygen concentration in the oxide semiconductor film introduced by the oxygen doping treatment is 1 × 10 ¹⁸ / cm ³ or more and 3 × 10 ²¹ / cm ³ or less.

Further, in the above method for manufacturing a semiconductor device, an oxide insulating film may be formed between the oxide semiconductor film and the aluminum oxide film.

In the process of manufacturing a transistor having an oxide semiconductor film, oxygen doping treatment is performed, and then the function of preventing water (including hydrogen) from entering the oxide semiconductor film and the function of preventing oxygen from being desorbed from the oxide semiconductor film are performed. By performing heat treatment with the aluminum oxide film provided,
In the film of the oxide semiconductor film (in the bulk) or at the interface between the insulating film and the oxide semiconductor film, at least one region (also referred to as an oxygen excess region) in which oxygen exceeding the chemical quantitative composition ratio of the film is present. ) Can be provided. The oxygen added by the oxygen doping treatment is
It may exist between the lattices of oxide semiconductors.

In addition, the oxide semiconductor film is dehydrated or dehydrogenated by heat treatment to remove impurities containing hydrogen atoms such as hydrogen atoms or water in the oxide semiconductor film to purify the oxide semiconductor film. Is preferable. The amount of oxygen added by the oxygen doping treatment is preferably larger than the amount of hydrogen in the oxide semiconductor film purified by the dehydration or dehydrogenation treatment.

The above-mentioned "oxygen doping treatment" means adding oxygen (including at least one of oxygen radicals, oxygen atoms, and oxygen ions) to the bulk. The term "bulk" is used for the purpose of clarifying that oxygen is added not only to the surface of the thin film but also to the inside of the thin film. Further, the "oxygen doping treatment" includes "oxygen ion implantation treatment" or "oxygen plasma doping" in which plasmatized oxygen is added to the bulk.

The effect of the above-described configuration, which is one aspect of the disclosed invention, can be easily understood by considering it as follows. However, it should be added that the following explanation is just one consideration.

In general, oxygen contained in an oxide semiconductor film dynamically repeats a reaction of bonding and desorption with a metal element in an oxide semiconductor as represented by the following formula (1). Since the metal element from which oxygen has been desorbed has an unbonded hand, oxygen deficiency exists at the location where oxygen is desorbed in the oxide semiconductor film.

The oxide semiconductor film according to one aspect of the disclosed invention can immediately compensate for the oxygen deficiency by containing excess oxygen (preferably excess oxygen from the stoichiometric ratio) in the film. .. Therefore, DOS (density of status) caused by oxygen deficiency existing in the membrane
e) can be reduced. For example, when the oxide semiconductor film contains an amount of oxygen corresponding to the stoichiometric composition ratio, the average density of DOS is 10 ¹⁸ cm ^-3 or more and 10 ¹⁹ cm ^−.
When it is about ³ or less, D in an oxide semiconductor containing oxygen in excess of the stoichiometric composition ratio.
The average density of the OS can be about 10 ¹⁵ cm ^-3 or more and 10 ¹⁶ cm ^-3 or less.

It has been confirmed that the larger the film thickness of the oxide semiconductor film, the larger the variation in the threshold voltage of the transistor. It can be inferred that this is because oxygen defects in the oxide semiconductor film contribute to the fluctuation of the threshold voltage, and the oxygen defects increase as the film thickness of the oxide semiconductor film increases. As described above, in the transistor according to one aspect of the disclosed invention, the oxygen content of the oxide semiconductor film is increased by the oxygen doping treatment, so that the film produced by the dynamic reaction of the above formula (1). It is possible to immediately compensate for the oxygen deficiency inside. Therefore, in the transistor according to one aspect of the disclosed invention, the time for forming the donor level due to the oxygen defect can be shortened, and the donor level can be substantially eliminated, so that the threshold voltage varies. Can be suppressed.

By allowing the oxide semiconductor film to contain excess oxygen and providing an aluminum oxide film on the oxide semiconductor film so that the oxygen is not released, at the interface between the oxide semiconductor and the layers in contact with each other above and below it. It is possible to prevent defects from being generated and increasing. That is, since the excess oxygen contained in the oxide semiconductor film acts to fill the oxygen vacancies, it is possible to provide a highly reliable semiconductor device having stable electrical characteristics.

A plan view and a cross-sectional view illustrating one form of a semiconductor device. The figure explaining one form of the manufacturing method of a semiconductor device. A plan view and a cross-sectional view illustrating one form of a semiconductor device. A plan view and a cross-sectional view illustrating one form of a semiconductor device. The figure explaining one form of the manufacturing method of a semiconductor device. A plan view and a cross-sectional view illustrating one form of a semiconductor device. The figure explaining one form of the semiconductor device. The figure explaining one form of the semiconductor device. The figure explaining one form of the semiconductor device. The figure explaining one form of the semiconductor device. The figure explaining one form of the semiconductor device. The figure explaining one form of the semiconductor device. The figure which shows the electronic device. The figure which shows the measurement result of SIMS. The figure which shows the measurement result of SIMS. The figure which shows the measurement result of TDS. The figure which shows the measurement result of TDS.

Hereinafter, embodiments of the invention disclosed in the present specification will be described in detail with reference to the drawings.
However, it is easily understood by those skilled in the art that the invention disclosed in the present specification is not limited to the following description, and its form and details may be changed in various ways. Further, the invention disclosed in the present specification is not construed as being limited to the description contents of the embodiments shown below.

The ordinal numbers attached as the first and second numbers are used for convenience and do not indicate the process order or the stacking order. In addition, this specification does not indicate a unique name as a matter for specifying the invention.

(Embodiment 1)
In the present embodiment, one embodiment of the semiconductor device and the method for manufacturing the semiconductor device will be described with reference to FIGS. 1 to 3. In the present embodiment, a transistor having an oxide semiconductor film is shown as an example of a semiconductor device.

FIG. 1 shows a cross-sectional view and a plan view of a bottom gate type transistor 410 as an example of a semiconductor device. 1 (A) is a plan view, and FIGS. 1 (B) and 1 (C) are cross-sectional views taken along the sections AB and CD in FIG. 1 (A). In FIG. 1A, a part of the components of the transistor 410 (for example, the insulating film 407) is omitted in order to avoid complication.

The transistor 410 shown in FIG. 1 has a gate electrode layer 40 on a substrate 400 having an insulating surface.
1. The gate insulating film 402, the oxide semiconductor film 403, the source electrode layer 405a, the drain electrode layer 405b, and the insulating film 407 are included.

In the transistor 410 shown in FIG. 1, the oxide semiconductor film 403 is subjected to oxygen doping treatment and has an oxygen excess region. By performing the oxygen doping treatment, the oxide semiconductor film 403 can contain a sufficient amount of oxygen to compensate for the oxygen deficiency in the film, so that the transistor 410 with improved reliability is realized.

Further, an aluminum oxide film is provided as the insulating film 407. Since aluminum oxide has a barrier function that makes it difficult for moisture, oxygen, and other impurities to permeate, it is possible to prevent impurities such as moisture from entering from the outside after the device is completed. In addition, it is possible to prevent oxygen from being released from the oxide semiconductor film 403. The insulating film 407 more preferably has an oxygen excess region.

Further, the gate insulating film 402 preferably has an oxygen excess region. Gate insulating film 402
When has an oxygen excess region, it is possible to prevent the movement of oxygen from the oxide semiconductor film 403 to the gate insulating film 402, and to supply oxygen from the gate insulating film 402 to the oxide semiconductor film 403. This is because it can also be done.

An insulator may be further provided on the transistor 410. Further, in order to electrically connect the source electrode layer 405a and the drain electrode layer 405b to the wiring, an opening may be formed in the gate insulating film 402 or the like. Further, a second gate electrode may be further provided above the oxide semiconductor film 403. The oxide semiconductor film 403 may be processed into an island shape.

FIGS. 2 (A) to 2 (D) show an example of a method for manufacturing the transistor 410.

First, a conductive film is formed on the substrate 400 having an insulating surface, and then the gate electrode layer 401 is formed by a photolithography step. The resist mask may be formed by an inkjet method. When the resist mask is formed by the inkjet method, the photomask is not used, so that the manufacturing cost can be reduced.

There is no major limitation on the substrate that can be used for the substrate 400 having an insulating surface, but at least it is necessary to have heat resistance enough to withstand the subsequent heat treatment. For example, glass substrates such as barium borosilicate glass and aluminoborosilicate glass, ceramic substrates,
A quartz substrate, a sapphire substrate, or the like can be used. Further, a single crystal semiconductor substrate such as silicon or silicon carbide, a polycrystalline semiconductor substrate, a compound semiconductor substrate such as silicon germanium, an SOI substrate, or the like can be applied, and a semiconductor element is provided on these substrates. It may be used as a substrate 400.

Moreover, you may use a flexible substrate as a substrate 400. When a flexible substrate is used, a transistor containing an oxide semiconductor film may be directly produced on the flexible substrate, or a transistor containing an oxide semiconductor film may be produced on another production substrate, and then flexible. It may be peeled off and transferred to the substrate.
In addition, in order to peel and transfer from the manufactured substrate to the flexible substrate, it is preferable to provide a peeling layer between the manufactured substrate and the transistor containing the oxide semiconductor film.

An insulating film serving as a base film may be provided between the substrate 400 and the gate electrode layer 401. The undercoat has a function of preventing the diffusion of impurity elements from the substrate 400, and has a laminated structure of one or more films selected from a silicon nitride film, a silicon oxide film, a silicon nitride film, or a silicon oxide film. Can be formed.

Further, the gate electrode layer 401 is made of a metal material such as molybdenum, titanium, tantalum, tungsten, aluminum, copper, neodymium, scandium or an alloy material containing these as a main component by a plasma CVD method or a sputtering method. It can be formed in layers or in layers.

Next, the gate insulating film 402 is formed on the gate electrode layer 401. In the present embodiment, a silicon oxide film is formed as the gate insulating film 402 by a plasma CVD method, a sputtering method, or the like. The gate insulating film 402 is a silicon oxide film and silicon nitride, silicon oxide, silicon nitride, aluminum oxide, aluminum nitride, aluminum nitride, aluminum nitride, hafnium oxide, gallium oxide, or a mixed material thereof. It may be a laminated structure of a film containing the film. However, it is preferable that the silicon oxide film has a structure in contact with the oxide semiconductor film 403 to be formed later.

Further, high-density plasma CVD using μ waves (for example, frequency 2.45 GHz) can form a high-quality insulating layer that is dense and has a high dielectric strength, and is therefore preferable to be used for forming the gate insulating film 402. This is because the high-purity oxide semiconductor and the high-quality gate insulating film are in close contact with each other, so that the interface state can be reduced and the interface characteristics can be improved.

Further, an insulating layer in which the film quality and the interface characteristics with the oxide semiconductor are modified by the heat treatment after the film formation may be used as the gate insulating film. In any case, not only the film quality as the gate insulating film is good, but also the interface level density with the oxide semiconductor can be reduced and a good interface can be formed.

It is preferable that the gate insulating film 402 has an oxygen excess region because the excess oxygen contained in the gate insulating film 402 can compensate for the oxygen deficiency of the oxide semiconductor film 403.

Next, an oxide semiconductor film 403 having a film thickness of 2 nm or more and 200 nm or less, preferably 5 nm or more and 30 nm or less is formed on the gate insulating film 402 (see FIG. 2A).

As the oxide semiconductor film 403, a metal oxide material containing two or more kinds selected from In, Ga, Zn and Sn may be used. For example, In-Sn-Ga-Zn-, which is a quaternary metal oxide.
O-based materials, In-Ga-Zn-O-based materials that are ternary metal oxides, In-Sn-Z
n-O-based material, In-Al-Zn-O-based material, Sn-Ga-Zn-O-based material, Al
-Ga-Zn-O-based material, Sn-Al-Zn-O-based material, In-Zn-O-based material which is a binary metal oxide, Sn-Zn-O-based material, Al- Zn-O-based material, Zn-M
g-O-based material, Sn-Mg-O-based material, In-Mg-O-based material, In-Ga-O-based material, In-O-based material, Sn-O-based material, Zn A −O-based material or the like may be used. Further, the oxide semiconductor may contain elements other than In, Ga, Sn and Zn, for example, SiO ₂ .

Here, for example, the In-Ga-Zn-O-based oxide semiconductor means an oxide semiconductor having indium (In), gallium (Ga), and zinc (Zn), and the composition ratio thereof does not matter. ..

Further, as the oxide semiconductor film 403, a thin film represented by the chemical formula InMO ₃ (ZnO) _m (m> 0) can be used. Here, M represents one or more metal elements selected from Zn, Ga, Al, Mn and Co. For example, as M, Ga, Ga and Al, Ga and Mn
, Or Ga and Co.

When an In—Zn—O-based material is used as the oxide semiconductor, the composition ratio of the target used is In: Zn = 50: 1 to 1: 2 in terms of atomic number ratio (In ₂ when converted to a molar ratio). O ₃
: ZnO = 25: 1 to 1: 4), preferably In: Zn = 20: 1 to 1: 1 (In ₂ O ₃ : ZnO = 10: 1 to 1: 2 in terms of molar ratio), more preferably. Is In: Zn = 1
It is set to 5: 1 to 1.5: 1 (in ₂ O ₃ : ZnO = 15: 2 to 3: 4 when converted to a molar ratio). For example, the target used for forming an In—Zn—O-based oxide semiconductor is Z> 1.5X + Y when the atomic number ratio is In: Zn: O = X: Y: Z.

The oxide semiconductor film is in a state of single crystal, polycrystal (also referred to as polycrystal), or amorphous.

Further, as the oxide semiconductor film 403, CAAC-OS (C Axis Aligned)
A Crystalline Oxide Semiconductor) membrane may be used.

The CAAC-OS film is neither completely single crystal nor completely amorphous. The CAAC-OS film is an oxide semiconductor film having a crystal-amorphous mixed phase structure having a crystal portion and an amorphous portion in an amorphous phase. In many cases, the crystal portion has a size that fits in a cube having a side of less than 100 nm. In addition, a transmission microscope (TEM: Transmission Electron M)
In the observation image by icroscopy), the boundary between the amorphous part and the crystal part contained in the CAAC-OS film is not clear. In addition, grain boundaries (also referred to as grain boundaries) cannot be confirmed on the CAAC-OS film by TEM. Therefore, the CAAC-OS film suppresses the decrease in electron mobility due to the grain boundaries.

The crystal part contained in the CAAC-OS film is aligned in a direction in which the c-axis is parallel to the normal vector of the surface to be formed of the CAAC-OS film or the normal vector of the surface of the CAAC-OS film, and is perpendicular to the ab plane. It has a triangular or hexagonal atomic arrangement when viewed from the direction, and metal atoms are arranged in layers or metal atoms and oxygen atoms are arranged in layers when viewed from the direction perpendicular to the c-axis. The directions of the a-axis and the b-axis may be different between different crystal portions. In the present specification, when it is simply described as vertical, the range of 85 ° or more and 95 ° or less is also included. In addition, when simply describing parallel, the range is also included within -5 ° or more and 5 ° or less.

In the CAAC-OS film, the distribution of crystal portions does not have to be uniform. For example, CAA
In the process of forming the C-OS film, when crystals are grown from the surface side of the oxide semiconductor film, the proportion of the crystal portion in the vicinity of the surface may be higher than that in the vicinity of the surface to be formed. Also, CA
By adding an impurity to the AC-OS film, the crystal part may become amorphous in the impurity-added region.

Since the c-axis of the crystal portion contained in the CAAC-OS film is aligned in the direction parallel to the normal vector of the surface to be formed or the normal vector of the surface of the CAAC-OS film, the shape of the CAAC-OS film (plane to be formed). Depending on the cross-sectional shape of the surface or the cross-sectional shape of the surface), they may face different directions. In addition, it should be noted
The direction of the c-axis of the crystal portion is parallel to the normal vector of the surface to be formed or the normal vector of the surface when the CAAC-OS film is formed. The crystal portion is formed by forming a film or by performing a crystal growth treatment such as a heat treatment after the film formation.

A transistor using a CAAC-OS film can reduce fluctuations in electrical characteristics due to irradiation with visible light or ultraviolet light. Therefore, the transistor has high reliability.

A part of oxygen constituting the CAAC-OS film may be replaced with nitrogen.

The oxide semiconductor film 403 is formed by a sputtering method, a molecular beam epitaxy method, an atomic layer deposition method, or a pulse laser vapor deposition method. Here, it can be formed by a sputtering method.

When the oxide semiconductor film 403 is used as a CAAC-OS film, the oxide semiconductor film 403 may be formed while heating the substrate 400, and the temperature for heating the substrate 400 is preferably 150 ° C. or higher and 450 ° C. or lower. The substrate temperature is 200 ° C. or higher and 350 ° C. or lower. By raising the temperature at which the substrate is heated when the oxide semiconductor film is formed, a CAAC-OS film in which the crystal portion occupies a large proportion of the amorphous portion can be obtained.

When the oxide semiconductor film 403 is formed by the sputtering method, it is preferable to reduce the hydrogen concentration contained in the oxide semiconductor film 403 as much as possible. In order to reduce the hydrogen concentration, high-purity rare gas (typically argon) from which impurities such as hydrogen, water, hydroxyl groups or hydrides have been removed, oxygen, as atmospheric gas to be supplied to the processing chamber of the sputtering apparatus, And a mixed gas of rare gas and oxygen is used as appropriate. Further, the exhaust of the treatment chamber may be a combination of a cryopump having a high water exhaust capacity and a sputter ion pump having a high hydrogen exhaust capacity.

Further, the gate insulating film 402 and the oxide semiconductor film 403 may be continuously formed without being released to the atmosphere. For example, after removing impurities containing hydrogen adhering to the surface of the gate electrode layer 401 provided on the substrate 400 by heat treatment or plasma treatment, the gate insulating film 402 is formed without being released to the atmosphere, followed by the atmosphere. The oxide semiconductor film 403 may be formed without releasing the oxide semiconductor film 403. By doing so, impurities containing hydrogen adhering to the surface of the gate electrode layer 401 can be reduced, and the interface between the gate electrode layer 401 and the gate insulating film 402 and the gate insulating film 402 and the oxide semiconductor film can be reduced. It is possible to suppress the adhesion of atmospheric components to the interface with the 403. As a result, a transistor 410 having good electrical characteristics and high reliability can be manufactured.

After forming the oxide semiconductor film 403, it is desirable to perform a heat treatment (first heat treatment) on the oxide semiconductor film 403. Excess hydrogen (including water and hydroxyl groups) in the oxide semiconductor film 403 can be removed by this first heat treatment. Furthermore, it is also possible to remove excess hydrogen (including water and hydroxyl groups) in the gate insulating film 402 by this first heat treatment. The temperature of the first heat treatment is 250 ° C. or higher and 700 ° C. or lower, preferably 450 ° C. or higher and 600 ° C. or lower.
Below, or less than the distortion point of the substrate.

For heat treatment, for example, the object to be processed is introduced into an electric furnace using a resistance heating element, etc.
It can be carried out at 450 ° C. for 1 hour. During this period, the oxide semiconductor film 403 is kept out of contact with the atmosphere so that water and hydrogen are not mixed.

The heat treatment apparatus is not limited to the electric furnace, and an apparatus that heats the object to be processed by heat conduction from a medium such as heated gas or heat radiation may be used. For example, GRTA (Gas Rap)
id Thermal Anneal) device, LRTA (Lamp Rapid The)
RTA (Rapid Thermal Anneal) such as rmal Anneal equipment
) The device can be used. The LRTA device is a device that heats an object to be processed by radiation of light (electromagnetic waves) emitted from lamps such as halogen lamps, metal halide lamps, xenon arc lamps, carbon arc lamps, high-pressure sodium lamps, and high-pressure mercury lamps.
The GRTA device is a device that performs heat treatment using a high-temperature gas. As the gas, a rare gas such as argon or an inert gas such as nitrogen that does not react with the object to be treated by heat treatment is used.

For example, as the first heat treatment, the object to be treated may be put into a heated inert gas atmosphere, heated for several minutes, and then subjected to a GRTA treatment for removing the object to be processed from the inert gas atmosphere. The GRTA treatment enables high temperature heat treatment in a short time. Further, it can be applied even under temperature conditions exceeding the heat resistant temperature of the object to be processed. The inert gas may be switched to a gas containing oxygen during the treatment. By performing the first heat treatment in an atmosphere containing oxygen,
This is because the defect level in the energy gap caused by oxygen deficiency can be reduced.

As the inert gas atmosphere, it is desirable to apply an atmosphere containing nitrogen or a rare gas (helium, neon, argon, etc.) as a main component and not containing water, hydrogen, or the like. For example, the purity of nitrogen and rare gases such as helium, neon, and argon to be introduced into the heat treatment apparatus is 6N (99.99999%) or more, preferably 7N (99.99999%) or more (
That is, the impurity concentration is 1 ppm or less, preferably 0.1 ppm or less).

By the way, since the above-mentioned heat treatment (first heat treatment) has the effect of removing hydrogen, water and the like,
The heat treatment can also be called a dehydration treatment, a dehydrogenation treatment, or the like. The dehydration treatment and the dehydrogenation treatment can be performed at a timing such as after the oxygen doping treatment. Further, such dehydration treatment and dehydrogenation treatment may be performed not only once but also a plurality of times.

Next, a conductive film to be a source electrode layer and a drain electrode layer (including a wiring formed by the same layer) is formed on the oxide semiconductor film 403, and this is processed to form a source electrode layer 405a and a drain. An electrode layer 405b is formed (see FIG. 2B).

As the conductive film used for the source electrode layer 405a and the drain electrode layer 405b, a material that can withstand the subsequent heat treatment step is used. For example, a metal film containing an element selected from Al, Cr, Cu, Ta, Ti, Mo, and W, or a metal nitride film containing the above-mentioned elements as a component (titanium nitride film, molybdenum nitride film, tungsten nitride film). Etc. can be used. Also, Al, C
A refractory metal film such as Ti, Mo, W or a metal nitride film thereof (titanium nitride film, molybdenum nitride film, tungsten nitride film) is laminated on one or both of the lower side or the upper side of the metal film such as u. It may be configured. Further, the conductive film used for the source electrode layer and the drain electrode layer may be formed of a conductive metal oxide. Conductive metal oxide, indium oxide _{(In 2 O} 3), tin oxide _(SnO 2), zinc oxide (ZnO), _(abbreviated as _{In 2 O 3 -SnO 2, ITO} ) of indium oxide and tin oxide, Indium zinc oxide (In ₂
O _3- ZnO) or a metal oxide material containing silicon oxide can be used.

It is desirable to optimize the etching conditions so that the oxide semiconductor film 403 is not etched and divided when the conductive film is etched. However, it is difficult to obtain the condition that only the conductive film is etched and the oxide semiconductor film 403 is not etched at all. When the conductive film is etched, only a part of the oxide semiconductor film 403 is etched, and a groove (recess) is formed. It may be an oxide semiconductor film having.

Next, the source electrode layer 405a and the drain electrode layer 405b are covered, and the oxide semiconductor film 40 is covered.
An insulating film 407 in contact with a part of 3 is formed.

An aluminum oxide film can be used as the insulating film 407. Aluminum oxide has a barrier function that makes it difficult for water, oxygen, and other impurities to permeate. Therefore, by providing the aluminum oxide film on the oxide semiconductor film 403, the aluminum oxide film functions as a passivation film and prevents impurities such as moisture from entering the oxide semiconductor film 403 from the outside after the device is completed. be able to. In addition, it is possible to prevent oxygen from being released from the oxide semiconductor film 403.

The insulating film 407 has a film thickness of at least 1 nm or more, and can be formed by appropriately using a method such as a sputtering method in which impurities such as water and hydrogen are not mixed into the insulating film 407. Insulating film 407
When hydrogen is contained in the oxide semiconductor film, the hydrogen penetrates into the oxide semiconductor film or oxygen is extracted from the oxide semiconductor film by hydrogen, and the back channel of the oxide semiconductor film becomes low resistance (N-type). This may result in the formation of parasitic channels. Therefore, it is important not to use hydrogen in the film forming method so that the insulating film 407 is a film containing as little hydrogen as possible.

As the sputter gas used for forming the insulating film 407, it is preferable to use a high-purity gas from which impurities such as hydrogen, water, hydroxyl groups and hydrides have been removed.

The insulating film 407 may have at least an aluminum oxide film, and may have a laminated structure with a film containing another inorganic insulating material.

Next, the oxide semiconductor film 403 is subjected to oxygen doping treatment to form an oxygen excess region (FIG. 2 (FIG. 2).
See C)). By performing the oxygen doping treatment, oxygen 421 is supplied to the oxide semiconductor film 403 to insulate the interface between the insulating film 407 and the oxide semiconductor film 403, in the oxide semiconductor film 403, or gate insulation with the oxide semiconductor film 403. At least one of the interfaces with the film 402 is excessively oxygenated. By forming an oxygen excess region on the oxide semiconductor film 403, the oxygen deficiency can be immediately compensated. Thereby, the charge capture center in the oxide semiconductor film 403 can be reduced.

The oxygen content of the oxide semiconductor film 403 is determined by oxygen doping treatment.
It should exceed the stoichiometric composition ratio of. For example, the peak oxygen concentration in the oxide semiconductor film 403 introduced by the oxygen doping treatment is 1 × 10 ¹⁸ / cm ³ or more and 3 × 10 ^21.
It is preferably / cm ³ or less. The doped oxygen 421 contains oxygen radicals, oxygen atoms, and / or oxygen ions. The oxygen excess region may be present in a part (including the interface) of the oxide semiconductor film.

Oxygen is one of the main component materials in oxide semiconductors. Therefore, the oxygen concentration in the oxide semiconductor film can be adjusted to SIMS (Secondary Ion Mass Spec).
It is difficult to make an accurate estimate using a method such as romery). That is, it can be said that it is difficult to determine whether or not oxygen is intentionally added to the oxide semiconductor film.

By the way, it is known that oxygen has isotopes such as ¹⁷ O and ¹⁸ O, and their abundance ratios in nature are about 0.037% and 0.204% of the total oxygen atoms, respectively. That is, since the concentrations of these isotopes in the oxide semiconductor film can be estimated by a method such as SIMS, the oxygen concentration in the oxide semiconductor film can be more accurately measured by measuring these concentrations. It may be possible to estimate. Therefore, by measuring these concentrations, it may be determined whether or not oxygen is intentionally added to the oxide semiconductor film.

Further, a part of oxygen 421 added (included) to the oxide semiconductor film may have an unbonded oxygen in the oxide semiconductor. This is because having an unbound hand allows hydrogen to be immobilized (non-movable ionization) by binding to hydrogen that may remain in the membrane.

The oxygen to be doped (oxygen radicals, oxygen atoms, and / or oxygen ions) may be supplied by a plasma generator using a gas containing oxygen, or may be supplied by an ozone generator. More specifically, for example, oxygen 421 is used by using an apparatus for performing etching processing on a semiconductor apparatus, an apparatus for performing ashing on a resist mask, or the like.
Can be subjected to oxygen doping treatment on the oxide semiconductor film 403.

The oxygen doping treatment of the oxide semiconductor film 403 may be performed at any timing after the oxide semiconductor film 403 is formed, for example, the source electrode layer 405a and the drain electrode layer 4.
It may be done before 05b formation.

After the oxygen doping treatment, a heat treatment (preferably a second heat treatment) is performed. The temperature of the heat treatment is
It is preferably 350 ° C. or higher and 650 ° C. or lower, more preferably 450 ° C. or higher and 650 ° C. or lower, or less than the distortion point of the substrate. The heat treatment involves nitrogen, oxygen, and ultra-dry air (water content is 20 pp).
It may be carried out in an atmosphere of m or less, preferably 1 ppm or less, more preferably 10 ppb or less) or a rare gas (argon, helium, etc.), but the atmosphere of the above nitrogen, oxygen, ultradry air, or rare gas. It is preferable that the gas does not contain water, hydrogen, or the like. Further, the purity of nitrogen, oxygen, or rare gas to be introduced into the heat treatment apparatus is 6N (99.99999%) or more, preferably 7N (99.99999%) or more (that is, the impurity concentration is 1 ppm or less, preferably 0).
.. 1 ppm or less) is preferable.

By the above steps, the oxide semiconductor film 403 in which the formation of oxygen deficiency is suppressed can be formed. By the second heat treatment, oxygen, which is one of the main component materials constituting the oxide semiconductor, may be supplied to the oxide semiconductor film 403 from the gate insulating film 402, which is an oxygen-containing insulating film. Further, when the oxide semiconductor film 403 is a CAAC-OS film, the crystal structure contained in the oxide semiconductor film 403 may be disturbed and amorphized by the oxygen doping treatment, but heat treatment is performed after the oxygen doping treatment. It is possible to crystallize again by performing.

The timing of the oxygen doping treatment and the heat treatment after the oxygen doping treatment (second heat treatment) is
Although not limited to the configuration of the present embodiment, the heat treatment needs to be performed at least after the insulating film 407 is formed. The aluminum oxide film used as the insulating film 407 has a high blocking effect (blocking effect) that does not allow the film to permeate both impurities such as hydrogen and moisture, and oxygen. By performing heat treatment after forming the insulating film 407, the insulating film 407 is heat-treated. This is because the release of oxygen from the oxide semiconductor film 403 can be prevented.

By applying dehydration or dehydrogenation treatment of the oxide semiconductor film and oxygen doping treatment, the oxide semiconductor film 403 is highly purified so as not to contain impurities other than its main component as much as possible, and is type i (
It can be an oxide semiconductor film that is as close as possible to an intrinsic semiconductor) or i-type. There are very few donor-derived carriers in the highly purified oxide semiconductor film 403 (close to zero).
The carrier concentration is less than 1 × 10 ¹⁴ / cm ³ , preferably less than 1 × 10 ¹² / cm ³ , and more preferably less than 1 × 10 ¹¹ / cm ³ .

The transistor 410 is formed by the above steps (see FIG. 2D). Transistor 410
By creating an oxygen excess region by oxygen doping treatment, the formation of oxygen deficiency in the oxide semiconductor film or at the interface is suppressed, and the donor level in the energy gap due to the oxygen deficiency is reduced or substantially. Can be eliminated. Further, by supplying oxygen to the oxide semiconductor film 403 by oxygen doping treatment or subsequent heat treatment, the oxygen deficiency of the oxide semiconductor film 403 can be compensated. Further, the supplied oxygen can immobilize the hydrogen ions remaining in the oxide semiconductor film 403. Therefore, the transistor 410 is
Fluctuations in electrical characteristics are suppressed and it is electrically stable.

Further, the transistor 410 is preferably subjected to a heat treatment for the purpose of dehydration or dehydrogenation, and the heat treatment removes impurities such as hydrogen, water, hydroxyl groups or hydrides (also referred to as hydrogen compounds) from the oxide semiconductor film. It can be a transistor including an oxide semiconductor film 403 that is intentionally excluded.

FIG. 3 shows another configuration example of the transistor according to the present embodiment. 3 (A) is a plan view of the transistor 420, and FIGS. 3 (B) and 3 (C) are cross-sectional views relating to the EF cross section and the GH cross section in FIG. 3 (A). In FIG. 3A, a part of the components of the transistor 420 (for example, the insulating film 407) is omitted in order to avoid complication.

Similar to the transistor 410 shown in FIG. 1, the transistor 420 shown in FIG. 3 has a gate electrode layer 401, a gate insulating film 402, and an oxide semiconductor film 40 on a substrate 400 having an insulating surface.
3. The source electrode layer 405a, the drain electrode layer 405b, and the insulating film 407 are included.

One of the differences between the transistor 420 shown in FIG. 3 and the transistor 410 shown in FIG. 1 is the stacking order of the source electrode layer 405a and the drain electrode layer 405b and the oxide semiconductor film 403. That is, the transistor 420 has a source electrode layer 405a in contact with the gate insulating film 402.
And a drain electrode layer 405b, and an oxide semiconductor film 403 provided on the source electrode layer 405a and the drain electrode layer 405b and in contact with at least a part of the gate insulating film 402. For details, the description of the transistor 410 can be referred to.

Even when the configuration shown in FIG. 3 is adopted, the same effect as when the configuration shown in FIG. 1 is adopted can be obtained.

The transistor shown in the present embodiment suppresses deterioration due to electrical bias stress and thermal stress by increasing the oxygen content of the oxide semiconductor film by oxygen doping treatment, and reduces deterioration due to light. Can be done. Further, it is possible to compensate for the oxygen deficiency in the film by forming an oxygen excess region in the oxide semiconductor film by the oxygen doping treatment. Furthermore, by removing impurities containing hydrogen atoms such as hydrogen, water, hydroxyl groups or hydrides (also referred to as hydrides) from the oxide semiconductor by heat treatment, oxidation with high purity and i-type (intrinsic) By including the physical semiconductor film, fluctuations in electrical characteristics such as the threshold voltage are suppressed, and an electrically stable transistor can be obtained.

As shown above, according to the present embodiment, it is possible to provide a semiconductor device using an oxide semiconductor having stable electrical characteristics. Further, it is possible to provide a highly reliable semiconductor device.

As described above, the configurations and methods shown in the present embodiment can be appropriately combined with the configurations and methods shown in other embodiments.

(Embodiment 2)
In the present embodiment, the semiconductor device and another embodiment of the method for manufacturing the semiconductor device are shown in FIGS. 4 to 6.
Will be described using. The same parts as those in the first embodiment or the parts having the same functions and the steps can be performed in the same manner as in the first embodiment, and the repeated description will be omitted. Further, detailed description of the same part will be omitted.

FIG. 4 shows a cross-sectional view and a plan view of the top gate type transistor 510 as an example of the semiconductor device. 4 (A) is a plan view, and FIGS. 4 (B) and 4 (C) are cross-sectional views relating to the IJ cross section and the KL cross section in FIG. 4 (A). In FIG. 4A, a part of the components of the transistor 510 (for example, the insulating film 407) is omitted in order to avoid complication.

The transistor 510 shown in FIG. 4 has an underlying insulating film 506 on a substrate 400 having an insulating surface.
, Oxide semiconductor film 403, source electrode layer 405a, drain electrode layer 405b, gate insulating film 502, gate electrode layer 401, and insulating film 407.

In the transistor 510 shown in FIG. 4, it is preferable that at least one of the underlying insulating film 506 and the gate insulating film 502 has an oxygen excess region. When the insulating film in contact with the oxide semiconductor film 403 has an oxygen excess region, the transfer of oxygen from the oxide semiconductor film 403 to the insulating film in contact with the oxide semiconductor film 403 can be prevented, and the oxide semiconductor film 403 and the insulating film are in contact with the oxide semiconductor film 403. This is because oxygen can be supplied from the in contact insulating film to the oxide semiconductor film 403.

5 (A) to 5 (D) show an example of a method for manufacturing the transistor 510.

First, the underlying insulating film 506 is formed on the substrate 400 having an insulating surface, and then the underlying insulating film 50
An oxide semiconductor film 403 is formed in contact with No. 6 (see FIG. 5 (A)). After forming the oxide semiconductor film 403, it is desirable to perform a heat treatment (first heat treatment) on the oxide semiconductor film 403.

In the present embodiment, a silicon oxide film is formed as the underlying insulating film 506 by a plasma CVD method, a sputtering method, or the like. The underlying insulating film 506 is a silicon oxide film and
Silicon nitride, silicon oxide, silicon nitride, aluminum oxide, aluminum nitride, aluminum nitride, aluminum nitride, hafnium oxide, gallium oxide,
Alternatively, it may have a laminated structure with a film containing a mixed material thereof. However, it is preferable that the silicon oxide film has a structure in contact with the oxide semiconductor film 403 to be formed later.

It is preferable that the underlying insulating film 506 has an oxygen excess region because the excess oxygen contained in the underlying insulating film 506 can compensate for the oxygen deficiency of the oxide semiconductor film 403. In order to form an oxygen excess region on the base insulating film 506, for example, the film may be formed in an oxygen atmosphere or a mixed atmosphere of oxygen and a rare gas. Alternatively, the heat treatment may be performed in an oxygen atmosphere.

Further, the underlying insulating film 506 and the oxide semiconductor film 403 may be continuously formed without being released to the atmosphere. For example, after removing impurities containing hydrogen adhering to the surface of the substrate 400 by heat treatment or plasma treatment, the underlying insulating film 506 is formed without being released to the atmosphere, and subsequently, an oxide semiconductor film is formed without being released to the atmosphere. 403 may be formed. By doing so, impurities containing hydrogen adhering to the surface of the substrate 400 can be reduced, and atmospheric components can be suppressed from adhering to the interface between the underlying insulating film 506 and the oxide semiconductor film 403. As a result, a transistor 510 having good electrical characteristics and high reliability can be manufactured.

Next, a conductive film to be a source electrode layer and a drain electrode layer (including a wiring formed by the same layer) is formed on the oxide semiconductor film 403 in the same manner as in the step shown in FIG. 2 (B). Then, this is processed to form the source electrode layer 405a and the drain electrode layer 405b (see FIG. 5B).

Next, the source electrode layer 405a and the drain electrode layer 405b are covered, and the oxide semiconductor film 40 is covered.
A gate insulating film 502 in contact with a part of 3 is formed.

The gate insulating film 502 can be formed by using a CVD method, a sputtering method, or the like.
Further, the gate insulating film 502, silicon oxide, silicon nitride, silicon oxynitride, silicon nitride oxide, tantalum oxide, hafnium oxide, yttrium oxide, hafnium silicate _{(HfSi x O y (x>} 0, y> 0)), hafnium aluminate (HfAl _x O _y (x
> 0, y> 0)), it is preferable to form the hafnium silicate to which nitrogen has been added, hafnium aluminate to which nitrogen has been added, and the like. The gate insulating film 502 may have a single-layer structure or a laminated structure by combining the above materials. The thickness thereof is not particularly limited, but when the semiconductor device is miniaturized, it is desirable to make it thin in order to ensure the operation of the transistor. For example, when silicon oxide is used, it can be 1 nm or more and 100 nm or less, preferably 10 nm or more and 50 nm or less.

As described above, when the gate insulating film is thinned, gate leakage due to the tunnel effect or the like becomes a problem. To solve the problem of gate leak, the gate insulating film 502 is provided with hafnium oxide, tantalum oxide, yttrium oxide, hafnium silicate, hafnium aluminate, hafnium silicate added with nitrogen, hafnium aluminate added with nitrogen,
It is preferable to use a high dielectric constant (high-k) material such as. By using the high-k material for the gate insulating film 502, it is possible to increase the film thickness in order to suppress the gate leak while ensuring the electrical characteristics. A laminated structure of a film containing a high-k material and a film containing any one of silicon oxide, silicon nitride, silicon oxide and silicon nitride may be used.

Next, the oxide semiconductor film 403 is subjected to oxygen doping treatment in the same manner as in the step shown in FIG. 2 (C) to form an oxygen excess region (see FIG. 5 (C)). By performing the oxygen doping treatment, oxygen 421 is supplied to the oxide semiconductor film 403, and the interface between the underlying insulating film 506 and the oxide semiconductor film 403, in the oxide semiconductor film 403, or the gate with the oxide semiconductor film 403. Oxygen is contained in at least one of the interfaces with the insulating film 502. By forming an oxygen excess region on the oxide semiconductor film 403, the oxygen deficiency can be immediately compensated. As a result, the oxide semiconductor film 40
The charge capture center in 3 can be reduced.

The oxygen doping treatment of the oxide semiconductor film 403 may be performed at any timing after the oxide semiconductor film 403 is formed, for example, the source electrode layer 405a and the drain electrode layer 4.
It may be done before 05b formation.

Next, after forming a conductive film on the gate insulating film 502, the gate electrode layer 401 is formed by a photolithography step. After that, the gate electrode layer 401 is covered, and the gate insulating film 502
An insulating film 407 in contact with the insulating film 407 is formed (see FIG. 5 (D)).

After forming the insulating film 407, a heat treatment (preferably a second heat treatment) is performed. The temperature of the heat treatment is preferably 350 ° C. or higher and 650 ° C. or lower, more preferably 450 ° C. or higher and 650 ° C. or lower, or lower than the strain point of the substrate. The heat treatment involves nitrogen, oxygen, and ultra-dry air (water content is 20p).
It may be carried out in an atmosphere of pm or less, preferably 1 ppm or less, more preferably 10 ppb or less) or a rare gas (argon, helium, etc.), but the atmosphere of the above nitrogen, oxygen, ultradry air, or rare gas. It is preferable that the gas does not contain water, hydrogen, or the like. Further, the purity of nitrogen, oxygen, or rare gas to be introduced into the heat treatment apparatus is 6N (99.99999%) or more, preferably 7N (99.99999%) or more (that is, the impurity concentration is 1 ppm or less, preferably 0.1 ppm). The following) is preferable.

The timing of the oxygen doping treatment and the heat treatment after the oxygen doping treatment (second heat treatment) is
Although not limited to the configuration of the present embodiment, the heat treatment needs to be performed at least after the insulating film 407 is formed. The aluminum oxide film used as the insulating film 407 has a high blocking effect (blocking effect) that does not allow the film to permeate both impurities such as hydrogen and moisture, and oxygen. By performing heat treatment after forming the insulating film 407, the insulating film 407 is heat-treated. This is because the release of oxygen from the oxide semiconductor film 403 can be prevented.

In the above steps, the transistor 51 including the oxide semiconductor film 403 that suppresses the formation of oxygen deficiency
0 is formed (see FIG. 5 (D)). The transistor 510 suppresses the formation of oxygen deficiency in the oxide semiconductor film or at the interface by creating an oxygen excess region by oxygen doping treatment, and reduces the donor level in the energy gap due to the oxygen deficiency, or It can be virtually eliminated. Further, by supplying oxygen to the oxide semiconductor film 403 by oxygen doping treatment or subsequent heat treatment, the oxygen deficiency of the oxide semiconductor film 403 can be compensated. Further, the supplied oxygen can immobilize the hydrogen ions remaining in the oxide semiconductor film 403. Therefore, the transistor 510 is electrically stable because the fluctuation of the electrical characteristics is suppressed.

Further, the transistor 510 is preferably subjected to a heat treatment for the purpose of dehydration or dehydrogenation, and the heat treatment removes impurities such as hydrogen, water, hydroxyl groups or hydrides (also referred to as hydrides) from the oxide semiconductor film. It can be a transistor containing an oxide semiconductor film 403 that is intentionally excluded. By applying dehydration or dehydrogenation treatment of the oxide semiconductor film and oxygen doping treatment, the oxide semiconductor film is highly purified so as not to contain impurities other than its main component as much as possible, and is i-type (intrinsic). It can be an oxide semiconductor film that is as close as possible to a semiconductor) or i-type. There are very few carriers (near zero) in the highly purified oxide semiconductor film 403.

FIG. 6 shows another configuration example of the transistor according to the present embodiment. 6 (A) is a plan view of the transistor 520, and FIGS. 6 (B) and 6 (C) are cross-sectional views relating to the MN cross section and the OP cross section in FIG. 6 (A). In FIG. 6A, a part of the components of the transistor 520 (for example, the insulating film 407) is omitted in order to avoid complication.

Similar to the transistor 510 shown in FIG. 4, the transistor 520 shown in FIG. 6 has an underlying insulating film 506, an oxide semiconductor film 403, and a source electrode layer 405 on a substrate 400 having an insulating surface.
a, drain electrode layer 405b, gate insulating film 502, gate electrode layer 401 and insulating film 40
Includes 7.

One of the differences between the transistor 520 shown in FIG. 6 and the transistor 510 shown in FIG. 4 is the stacking order of the source electrode layer 405a and the drain electrode layer 405b and the oxide semiconductor film 403. That is, the transistor 520 is an oxide semiconductor provided on the source electrode layer 405a and the drain electrode layer 405b in contact with the underlying insulating film 506, and on the source electrode layer 405a and the drain electrode layer 405b, and at least partially in contact with the underlying insulating film 506. It has a film 403 and. For details, the description of the transistor 510 can be taken into consideration.

Even when the configuration shown in FIG. 6 is adopted, the same effect as when the configuration shown in FIG. 4 is adopted can be obtained.

The transistor shown in the present embodiment suppresses deterioration due to electrical bias stress and thermal stress by increasing the oxygen content of the oxide semiconductor film by oxygen doping treatment, and reduces deterioration due to light. Can be done. Further, it is possible to compensate for the oxygen deficiency in the film by forming an oxygen excess region in the oxide semiconductor film by the oxygen doping treatment. Furthermore, by removing impurities containing hydrogen atoms such as hydrogen, water, hydroxyl groups or hydrides (also referred to as hydrides) from the oxide semiconductor by heat treatment, oxidation with high purity and i-type (intrinsic) By including the physical semiconductor film, fluctuations in electrical characteristics such as the threshold voltage are suppressed, and an electrically stable transistor can be obtained.

As shown above, according to the present embodiment, it is possible to provide a semiconductor device using an oxide semiconductor having stable electrical characteristics. Further, it is possible to provide a highly reliable semiconductor device.

As described above, the configurations and methods shown in the present embodiment can be appropriately combined with the configurations and methods shown in other embodiments.

(Embodiment 3)
A semiconductor device (also referred to as a display device) having a display function can be manufactured using the transistors illustrated in the first or second embodiment. Further, a part or the whole of the drive circuit including the transistor can be integrally formed on the same substrate as the pixel portion to form a system on panel.

In FIG. 8A, the pixel portion 4002 provided on the first substrate 4001 is the pixel portion 40.
It is sealed by a sealing material 4005 provided so as to surround 02 and a second substrate 4006. In FIG. 8A, a single crystal semiconductor film or a polycrystalline semiconductor film is formed on a separately prepared substrate in a region different from the region surrounded by the sealing material 4005 on the first substrate 4001. , Scan line drive circuit 4004 and signal line drive circuit 4003 are mounted. Further, the signal line drive circuit 4003, the scanning line drive circuit 4004, and the pixel unit 400.
Various signals and potentials given to 2 are FPC (Flexible printed ci).
It is supplied from rcuit) 4018a and 4018b.

In FIGS. 8B and 8C, a sealing material 4005 is provided so as to surround the pixel portion 4002 provided on the first substrate 4001 and the scanning line drive circuit 4004. A second substrate 4006 is provided on the pixel unit 4002 and the scanning line drive circuit 4004. Therefore, the pixel unit 4002 including the display element and the scanning line drive circuit 4004 are connected to the first substrate 400.
1 is sealed together with the sealing material 4005 and the second substrate 4006. FIG. 8 (B
) (C), a signal formed of a single crystal semiconductor film or a polycrystalline semiconductor film on a separately prepared substrate in a region different from the region surrounded by the sealing material 4005 on the first substrate 4001. The line drive circuit 4003 is mounted. In FIGS. 8B and 8C, various signals and potentials given to the signal line driving circuit 4003, the scanning line driving circuit 4004, and the pixel unit 4002 are supplied from the FPC 4018.

Further, in FIGS. 8B and 8C, a signal line drive circuit 4003 is separately formed, and the first substrate 4 is formed.
Although an example implemented in 001 is shown, the present embodiment is not limited to this configuration. The scanning line drive circuit may be separately formed and mounted, or only a part of the signal line driving circuit or a part of the scanning line driving circuit may be separately formed and mounted.

The method of connecting the separately formed drive circuit is not particularly limited, and COG (Ch) is not particularly limited.
ip On Glass) method, wire bonding method, or TAB (Tape A)
An automated Bonding) method or the like can be used. FIG. 8 (A) shows C
This is an example of mounting the signal line drive circuit 4003 and the scanning line drive circuit 4004 by the OG method.
FIG. 8B is an example of mounting the signal line drive circuit 4003 by the COG method, and FIG. 8C is shown in FIG.
) Is an example of mounting the signal line drive circuit 4003 by the TAB method.

Further, the display device includes a panel in which the display element is sealed, and a module in which an IC or the like including a controller is mounted on the panel.

The display device in the present specification refers to an image display device, a display device, or a light source (including a lighting device). In addition, an IC (integrated circuit) is directly mounted on a connector, for example, a module to which FPC or TAB tape or TCP is attached, a module having a printed wiring board at the end of TAB tape or TCP, or a display element by the COG method. All modules shall be included in the display device.

Further, the pixel portion and the scanning line drive circuit provided on the first substrate have a plurality of transistors, and the transistors illustrated in the first or second embodiment can be applied.

The display elements provided in the display device include a liquid crystal element (also called a liquid crystal display element) and a light emitting element (also called a liquid crystal display element).
(Also referred to as a light emitting display element), can be used. The light emitting element includes an element whose brightness is controlled by current or voltage in its category, and specifically, an inorganic EL (Electro).
Luminescence), organic EL and the like are included. Further, a display medium whose contrast changes due to an electric action, such as electronic ink, can also be applied.

A form of the semiconductor device will be described with reference to FIGS. 9 to 11. 9 to 11 correspond to the cross-sectional views taken along the line QR of FIG. 8 (B).

As shown in FIGS. 9 to 11, the semiconductor device includes the connection terminal electrode layer 4015 and the terminal electrode layer 40.
The connection terminal electrode layer 4015 and the terminal electrode layer 4016 are electrically connected to the terminals of the FPC 4018 via the anisotropic conductive film 4019.

The connection terminal electrode layer 4015 is formed of the same conductive film as the first electrode layer 4030, and the terminal electrode layer 4016 is formed of the same conductive film as the source electrode layer and drain electrode layer of the transistors 4010 and 4011.

Further, the pixel unit 4002 provided on the first substrate 4001 and the scanning line drive circuit 4004
A plurality of transistors are provided, and FIGS. 9 to 11 exemplify the transistor 4010 included in the pixel unit 4002 and the transistor 4011 included in the scanning line drive circuit 4004. In FIG. 9, the insulating film 4020 and the insulating film 40 are on the transistors 4010 and 4011.
24 is provided, and in FIGS. 10 and 11, an insulating film 4021 is further provided. The insulating film 4023 is an insulating film that functions as a base film.

In the present embodiment, the transistor 4010 and the transistor 4011 are used as the first embodiment.
Alternatively, the transistor shown in 2 can be applied.

The transistor 4010 and the transistor 4011 are transistors having an oxide semiconductor film that is highly purified and suppresses the formation of oxygen deficiency. Therefore, the transistor 4010 and the transistor 4011 are electrically stable because the fluctuation of the electrical characteristics is suppressed.

Therefore, it is possible to provide a highly reliable semiconductor device as the semiconductor device of the present embodiment shown in FIGS. 9 to 11.

Further, in the present embodiment, the conductive layer is provided on the insulating film at a position overlapping the channel forming region of the oxide semiconductor film of the transistor 4011 for the drive circuit. By providing the conductive layer at a position overlapping the channel forming region of the oxide semiconductor film, the amount of change in the threshold voltage of the transistor 4011 before and after the BT test can be further reduced. Further, the conductive layer may have the same potential as the gate electrode layer of the transistor 4011 or may be different, and may function as the second gate electrode layer. Further, the potential of the conductive layer may be GND, 0V, or a floating state.

Further, the conductive layer also has a function of shielding an external electric field, that is, a function of preventing the external electric field from acting on the inside (circuit portion including a thin film transistor) (particularly, an electrostatic shielding function against static electricity). The shielding function of the conductive layer can prevent the electrical characteristics of the transistor from fluctuating due to the influence of an external electric field such as static electricity.

The transistor 4010 provided in the pixel unit 4002 is electrically connected to the display element to form a display panel. The display element is not particularly limited as long as it can display, and various display elements can be used.

FIG. 9 shows an example of a liquid crystal display device using a liquid crystal element as a display element. In FIG. 9, the liquid crystal element 4013, which is a display element, includes a first electrode layer 4030, a second electrode layer 4031, and a liquid crystal layer 4008. Insulating films 4032 and 4033 that function as alignment films are provided so as to sandwich the liquid crystal layer 4008. The second electrode layer 4031 is provided on the side of the second substrate 4006, and the first electrode layer 4030 and the second electrode layer 4031 are laminated via the liquid crystal layer 4008.

Further, 4035 is a columnar spacer obtained by selectively etching the insulating film.
It is provided to control the film thickness (cell gap) of the liquid crystal layer 4008. A spherical spacer may be used.

When a liquid crystal element is used as the display element, a thermotropic liquid crystal, a low molecular weight liquid crystal, a polymer liquid crystal, a polymer dispersed liquid crystal, a strong dielectric liquid crystal, an anti-strong dielectric liquid crystal, or the like can be used. Depending on the conditions, these liquid crystal materials exhibit a cholesteric phase, a smectic phase, a cubic phase, a chiral nematic phase, an isotropic phase and the like.

Further, a liquid crystal showing a blue phase without using an alignment film may be used. The blue phase is one of the liquid crystal phases, and is a phase that appears immediately before the transition from the cholesteric phase to the isotropic phase when the temperature of the cholesteric liquid crystal is raised. Since the blue phase is expressed only in a narrow temperature range, a liquid crystal composition mixed with a chiral agent of several weight% or more is used for the liquid crystal layer in order to improve the temperature range.
A liquid crystal composition containing a liquid crystal exhibiting a blue phase and a chiral agent has a short response speed and is optically isotropic, so that no orientation treatment is required and the viewing angle dependence is small. Further, since the alignment film does not need to be provided, the rubbing process is not required, so that the electrostatic breakdown caused by the rubbing process can be prevented, and the defects and breakage of the liquid crystal display device during the manufacturing process can be reduced. ..
Therefore, it is possible to improve the productivity of the liquid crystal display device. A transistor using an oxide semiconductor film may deviate from the design range due to a significant change in the electrical characteristics of the transistor due to the influence of static electricity. Therefore, it is more effective to use a blue phase liquid crystal material for a liquid crystal display device having a transistor using an oxide semiconductor film.

The intrinsic resistance of the liquid crystal material is 1 × 10 ⁹ Ω · cm or more, preferably 1 × 10 ¹¹
It is Ω · cm or more, and more preferably 1 × 10 ¹² Ω · cm or more. The value of the intrinsic resistance in the present specification is a value measured at 20 ° C.

The size of the holding capacitance provided in the liquid crystal display device is set so that the electric charge can be held for a predetermined period in consideration of the leakage current of the transistor arranged in the pixel portion and the like. The size of the holding capacitance may be set in consideration of the off-current of the transistor and the like. By using a transistor having an oxide semiconductor film having a high purity and an excess oxygen region, a holding capacity having a capacity of 1/3 or less, preferably 1/5 or less of the liquid crystal capacity of each pixel is provided. Is enough.

The transistor having an oxide semiconductor film with high purity and suppressed formation of oxygen deficiency used in the present embodiment can reduce the current value (off current value) in the off state. Therefore, the holding time of an electric signal such as an image signal can be lengthened, and the writing interval can be set long when the power is on. Therefore, the frequency of refresh operations can be reduced.
It has the effect of suppressing power consumption.

Further, the transistor having the oxide semiconductor film which is highly purified and suppresses the formation of oxygen deficiency used in the present embodiment can be driven at high speed because a relatively high field effect mobility can be obtained. For example, by using such a transistor capable of high-speed driving in a liquid crystal display device, it is possible to form a switching transistor in a pixel portion and a driver transistor used in a driving circuit portion on the same substrate. That is, since it is not necessary to separately use a semiconductor device formed of a silicon wafer or the like as a drive circuit, the number of parts of the semiconductor device can be reduced. Also, by using a transistor that can be driven at high speed in the pixel section,
It is possible to provide a high-quality image.

The liquid crystal display device has a TN (Twisted Nematic) mode and an IPS (In-P).
lane-Switching mode, FFS (Fringe Field Switch)
ching) mode, ASM (Axially Symmetrically named)
Micro-cell mode, OCB (Optical Compensated B)
irrefringence mode, FLC (Ferroelectric Liqui)
d Crystal) mode, AFLC (Antiferroelectric Liq)
A uid Crystal) mode or the like can be used.

Further, a normally black type liquid crystal display device, for example, a transmissive type liquid crystal display device adopting a vertical orientation (VA) mode may be used. There are several vertical orientation modes,
For example, MVA (Multi-Domain Vertical Element)
A mode, a PVA (Patterned Vertical Alignment) mode, an ASV mode and the like can be used. It can also be applied to a VA type liquid crystal display device. The VA type liquid crystal display device is a kind of method for controlling the arrangement of liquid crystal molecules on a liquid crystal display panel. The VA type liquid crystal display device is a system in which liquid crystal molecules are oriented in the direction perpendicular to the panel surface when no voltage is applied. In addition, pixels are divided into several areas (
It is possible to use a method called multi-domain or multi-domain design, which is divided into sub-pixels) and devised to defeat molecules in different directions.

Further, in the display device, an optical member (optical substrate) such as a black matrix (light-shielding layer), a polarizing member, a retardation member, and an antireflection member is appropriately provided. For example, circular polarization using a polarizing substrate and a retardation substrate may be used. Further, a backlight, a side light or the like may be used as the light source.

Further, as the display method in the pixel unit, a progressive method, an interlaced method, or the like can be used. Further, the color elements controlled by the pixels at the time of color display are not limited to the three colors of RGB (R represents red, G represents green, and B represents blue). For example, RGBW (W stands for white)
, Or RGB with one or more colors such as yellow, cyan, and magenta added. In addition, it should be noted
The size of the display area may be different for each dot of the color element. However, the disclosed invention is not limited to the display device for color display, and can be applied to the display device for monochrome display.

Further, as a display element included in the display device, a light emitting element that utilizes electroluminescence can be applied. Light emitting devices that utilize electroluminescence are distinguished by whether the light emitting material is an organic compound or an inorganic compound. Generally, the former is organic E.
The L element and the latter are called inorganic EL elements.

In the organic EL element, by applying a voltage to the light emitting element, electrons and holes are injected into a layer containing a luminescent organic compound from a pair of electrodes, and a current flows. Then, when those carriers (electrons and holes) are recombined, the luminescent organic compound forms an excited state, and when the excited state returns to the ground state, it emits light. From such a mechanism, such a light emitting element is called a current excitation type light emitting element.

The inorganic EL element is classified into a dispersed inorganic EL element and a thin film type inorganic EL element according to the element configuration. The dispersed inorganic EL element has a light emitting layer in which particles of a light emitting material are dispersed in a binder, and the light emitting mechanism is donor-acceptor recombination type light emission utilizing a donor level and an acceptor level. In the thin film type inorganic EL element, the light emitting layer is sandwiched between the dielectric layers,
Furthermore, it has a structure in which it is sandwiched between electrodes, and the light emission mechanism is localized light emission that utilizes the inner-shell electronic transition of metal ions. Here, an organic EL element will be used as the light emitting element.

The light emitting element may have at least one of a pair of electrodes translucent in order to extract light. Then, a transistor and a light emitting element are formed on the substrate, and the top surface injection that extracts light emission from the surface opposite to the substrate, the bottom surface injection that extracts light emission from the surface on the substrate side, and the surface on the substrate side and the surface opposite to the substrate. There is a light emitting element having a double-sided injection structure that extracts light from the light emitting device, and any light emitting element having an injection structure can be applied.

FIG. 10 shows an example of a light emitting device using a light emitting element as a display element. The light emitting element 4513, which is a display element, is electrically connected to the transistor 4010 provided in the pixel unit 4002. The configuration of the light emitting element 4513 is a laminated structure of the first electrode layer 4030, the electroluminescent layer 4511, and the second electrode layer 4031, but is not limited to the configuration shown in FIG. Light emitting element 4
The configuration of the light emitting element 4513 can be appropriately changed according to the direction of the light extracted from the 513 and the like.

The partition wall 4510 is formed by using an organic insulating material or an inorganic insulating material. In particular, it is preferable to use a photosensitive resin material to form an opening on the first electrode layer 4030 so that the side wall of the opening is an inclined surface formed with a continuous curvature.

The electroluminescent layer 4511 may be composed of a single layer or may be configured such that a plurality of layers are laminated.

A protective film may be formed on the second electrode layer 4031 and the partition wall 4510 so that oxygen, hydrogen, water, carbon dioxide, etc. do not enter the light emitting element 4513. As the protective film, a silicon nitride film, a silicon oxide film, a DLC film, or the like can be formed. In addition, the first substrate 400
Filler 45 in the space sealed by the first, second substrate 4006, and sealing material 4005.
14 is provided and sealed. It is preferable to package (enclose) with a protective film (bonded film, ultraviolet curable resin film, etc.) or a cover material having high airtightness and little degassing so as not to be exposed to the outside air.

As the filler 4514, in addition to an inert gas such as nitrogen or argon, an ultraviolet curable resin or a thermosetting resin can be used, and PVC (polyvinyl chloride), acrylic resin, polyimide, epoxy resin, silicone resin, PVB ( Polyvinyl chloride) or EVA
(Ethylene vinyl acetate) can be used. For example, nitrogen may be used as the filler.

If necessary, a polarizing plate or a circular polarizing plate (including an elliptical polarizing plate) is provided on the ejection surface of the light emitting element.
An optical film such as a retardation plate (λ / 4 plate, λ / 2 plate) or a color filter may be appropriately provided. Further, an antireflection film may be provided on the polarizing plate or the circular polarizing plate. For example, it is possible to apply an anti-glare treatment that can diffuse the reflected light due to the unevenness of the surface and reduce the reflection.

It is also possible to provide electronic paper for driving electronic ink as a display device. Electronic paper is also called an electrophoresis display device (electrophoresis display), and has the advantages of being as easy to read as paper, having lower power consumption than other display devices, and being able to have a thin and light shape. ing.

The electrophoretic display device may have various forms, but a plurality of microcapsules containing a first particle having a positive charge and a second particle having a negative charge are dispersed in a solvent or a solute. By applying an electric field to the microcapsules, the particles in the microcapsules are moved in opposite directions and only the color of the particles aggregated on one side is displayed. The first particle or the second particle contains a dye and does not move in the absence of an electric field. Further, the color of the first particle and the color of the second particle are different (including colorless).

As described above, the electrophoresis display device is a display utilizing the so-called dielectrophoretic effect in which a substance having a high dielectric constant moves to an electric field region having a high dielectric constant.

The microcapsules dispersed in a solvent are called electronic inks, and the electronic inks can be printed on the surface of glass, plastic, cloth, paper, or the like. In addition, color display is also possible by using a color filter or particles having a dye.

The first particles and the second particles in the microcapsules are a conductor material, an insulator material, and the like.
A kind of material selected from a semiconductor material, a magnetic material, a liquid crystal material, a ferroelectric material, an electroluminescent material, an electrochromic material, a magnetic migration material, or a composite material thereof may be used.

Further, as the electronic paper, a display device using a twist ball display method can also be applied. In the twist ball display method, spherical particles painted in white and black are arranged between a first electrode layer and a second electrode layer, which are electrode layers used for a display element, and the first electrode layer and the first electrode layer are arranged. This is a method of displaying by controlling the orientation of spherical particles by causing a potential difference in the electrode layer of 2.

FIG. 11 shows an active matrix type electronic paper as a form of a semiconductor device. The electronic paper of FIG. 11 is an example of a display device using the twist ball display method. The twist ball display method displays by arranging spherical particles painted in black and white between the electrode layers used for the display element and controlling the orientation of the spherical particles by causing a potential difference between the electrode layers. The method.

Between the first electrode layer 4030 connected to the transistor 4010 and the second electrode layer 4031 provided on the second substrate 4006, a black region 4615a and a white region 4615a and a white region are contained in a cavity 4612 filled with a liquid. Spherical particles 4613 including spherical particles having 4615b are provided, and the periphery of the spherical particles 4613 is filled with a filler 4614 such as resin. The second electrode layer 4031 corresponds to the common electrode layer (counter electrode layer). The second electrode layer 4031
It is electrically connected to the common potential line.

In FIGS. 9 to 11, as the first substrate 4001 and the second substrate 4006, a flexible substrate can be used in addition to the glass substrate, for example, a translucent plastic substrate or the like. Can be used. As a plastic, FRP (Fibergla)
An ss-Reinforced Plastics board, a PVF (polyvinyl fluoride) film, a polyester film or an acrylic resin film can be used.
Further, a sheet having a structure in which an aluminum foil is sandwiched between a PVC film or a polyester film can also be used.

In the present embodiment, a silicon oxide film is used as the insulating film 4020, and an aluminum oxide film is used as the insulating film 4024. The insulating film 4020 and the insulating film 4024 can be formed by a sputtering method or a plasma CVD method.

The aluminum oxide film provided as the insulating film 4024 on the oxide semiconductor film has a high blocking effect (blocking effect) that does not allow the film to permeate both impurities such as hydrogen and water and oxygen.

Therefore, the aluminum oxide film is a variable factor of hydrogen during and after the production process.
It functions as a protective film that prevents impurities such as moisture from being mixed into the oxide semiconductor film and the release of oxygen, which is a main component material constituting the oxide semiconductor, from the oxide semiconductor film.

Further, the silicon oxide film provided as the insulating film 4020 in contact with the oxide semiconductor film has a function of supplying oxygen to the oxide semiconductor film. Therefore, the insulating film 4020 is preferably an oxide insulating film containing a large amount of oxygen.

The transistor 4010 and the transistor 4011 have an oxide semiconductor film that is highly purified and suppresses the formation of oxygen deficiency. Further, the transistor 4010 and the transistor 4011 have a silicon oxide film as a gate insulating film. The oxide semiconductor film contained in the transistor 4010 and the transistor 4011 forms a region having more oxygen than the chemical quantitative composition ratio by oxygen doping treatment, and heat treatment after doping is performed on the oxide semiconductor film. Insulation film 4
Since the operation is performed with the aluminum oxide film provided as 024, it is possible to prevent oxygen from being released from the oxide semiconductor film by the heat treatment. Therefore, the obtained oxide semiconductor film can be a film containing a region in which the oxygen content is more than the stoichiometric ratio.

Further, the oxide semiconductor film contained in the transistor 4010 and the transistor 4011 is dehydrogenated or dehydrogenated by at least one of heat treatment after film formation of the oxide semiconductor film and heat treatment after oxygen doping treatment. It is a pure film. Therefore, by using the oxide semiconductor film for the transistor 4010 and the transistor 4011, it is possible to reduce the variation in the threshold voltage Vth of the transistor and the shift ΔVth of the threshold voltage due to oxygen deficiency.

Further, as the insulating film 4021 that functions as a flattening insulating film, an organic material having heat resistance such as acrylic resin, polyimide, benzocyclobutene resin, polyamide, and epoxy resin can be used. In addition to the above organic materials, low dielectric constant materials (low-k materials), siloxane-based resins, PSG (phosphorus glass), BPSG (phosphorus glass) and the like can be used. The insulating film 4021 may be formed by laminating a plurality of insulating films formed of these materials.

The method for forming the insulating film 4021 is not particularly limited, and a sputtering method, S.
OG method, spin coat, dip, spray application, droplet ejection method (inkprint method, etc.),
Screen printing, offset printing, doctor knives, roll coaters, curtain coaters, knife coaters and the like can be used.

The display device transmits light from a light source or a display element to perform display. Therefore, all the thin films such as the substrate, the insulating film, and the conductive film provided in the pixel portion through which light is transmitted are made translucent with respect to light in the wavelength region of visible light.

In the first electrode layer and the second electrode layer (also referred to as pixel electrode layer, common electrode layer, counter electrode layer, etc.) for applying a voltage to the display element, the direction of the light to be taken out, the place where the electrode layer is provided, and Translucency and reflectivity may be selected according to the pattern structure of the electrode layer.

The first electrode layer 4030 and the second electrode layer 4031 are indium oxide containing tungsten oxide, indium zinc oxide containing tungsten oxide, indium oxide containing titanium oxide, indium tin oxide containing titanium oxide, and indium. Tin oxide (hereinafter referred to as ITO.
), Indium zinc oxide, indium tin oxide to which silicon oxide is added, graphene, and other conductive materials having translucency can be used.

Further, the first electrode layer 4030 and the second electrode layer 4031 are tungsten (W), molybdenum (Mo), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (N).
metal such as b), tantalum (Ta), chromium (Cr), cobalt (Co), nickel (Ni), titanium (Ti), platinum (Pt), aluminum (Al), copper (Cu), silver (Ag), etc. ,
Alternatively, it can be formed from the alloy thereof or the metal nitride thereof using one or more kinds.

Further, as the first electrode layer 4030 and the second electrode layer 4031, a conductive composition containing a conductive polymer (also referred to as a conductive polymer) can be used. As the conductive polymer, a so-called π-electron conjugated conductive polymer can be used. For example, polyaniline or a derivative thereof, polypyrrole or a derivative thereof, polythiophene or a derivative thereof, or a copolymer consisting of two or more kinds of aniline, pyrrole and thiophene or a derivative thereof may be mentioned.

Further, since the transistor is easily destroyed by static electricity or the like, it is preferable to provide a protection circuit for protecting the drive circuit. The protection circuit is preferably configured by using a non-linear element.

By applying the transistor shown in the first or second embodiment as described above, it is possible to provide a semiconductor device having various functions.

(Embodiment 4)
Using the transistors illustrated in the first or second embodiment, a semiconductor device having an image sensor function for reading information on an object can be manufactured.

FIG. 12A shows an example of a semiconductor device having an image sensor function. FIG. 12A is an equivalent circuit of a photosensor, and FIG. 12B is a cross-sectional view showing a part of the photosensor.

In the photodiode 602, one electrode is electrically connected to the photodiode reset signal line 658, and the other electrode is electrically connected to the gate of the transistor 640. Transistor 640
Is electrically connected to one of the source or drain to the photosensor reference signal line 672 and the other of the source or drain to one of the source or drain of the transistor 656. The transistor 656 is electrically connected to the gate signal line 659 at the gate and to the photosensor output signal line 671 at the other end of the source or drain.

In the circuit diagram of the present specification, "OS" is described as the symbol of the transistor using the oxide semiconductor film so that it can be clearly identified as the transistor using the oxide semiconductor film. In FIG. 12A, the transistor 640 and the transistor 656 are the first embodiment.
Alternatively, it is a transistor using an oxide semiconductor film in which an oxygen excess region is formed by oxygen doping treatment as shown in 2 transistors.

FIG. 12B shows the photodiode 602 and the transistor 640 in the photosensor.
A photodiode 602 and a transistor 640 that function as sensors are provided on a substrate 601 (TFT substrate) having an insulating surface. A substrate 613 is provided on the photodiode 602 and the transistor 640 by using an adhesive layer 608.

An insulating film 631, an insulating film 632, an interlayer insulating film 633, and an interlayer insulating film 634 are provided on the transistor 640. The photodiode 602 is provided on the interlayer insulating film 633 and is provided.
Between the electrode layer 641a formed on the interlayer insulating film 633 and the electrode layer 642 provided on the interlayer insulating film 634, the first semiconductor film 606a and the second semiconductor film 6 are sequentially formed from the interlayer insulating film 633 side.
It has a structure in which 06b and a third semiconductor film 606c are laminated.

The electrode layer 641a is electrically connected to the conductive layer 643 formed on the interlayer insulating film 634, and the electrode layer 642 is electrically connected to the gate electrode layer 645 via the electrode layer 641b. The gate electrode layer 645 is electrically connected to the gate electrode layer of the transistor 640, and the photodiode 602 is electrically connected to the transistor 640.

Here, a semiconductor film having a p-type conductive type as the first semiconductor film 606a, a high-resistance semiconductor film (I-type semiconductor film) as the second semiconductor film 606b, and an n-type conductive type as the third semiconductor film 606c are used. An example is a pin-type photodiode in which a semiconductor film is laminated.

The first semiconductor film 606a is a p-type semiconductor film, and can be formed of an amorphous silicon film containing an impurity element that imparts the p-type. The first semiconductor film 606a is formed by a plasma CVD method using a semiconductor material gas containing an impurity element of Group 13 (for example, boron (B)). Silane (SiH ₄ ) may be used as the semiconductor material gas. Or S
i ₂ H ₆ , SiH ₂ Cl ₂ , SiHCl ₃ , SiCl ₄ , SiF _{4, and the} like may be used. Further, after forming an amorphous silicon film containing no impurity element, the impurity element may be introduced into the amorphous silicon film by using a diffusion method or an ion implantation method. It is preferable to diffuse the impurity element by heating or the like after introducing the impurity element by an ion implantation method or the like. In this case, as a method for forming the amorphous silicon film, the LPCVD method, the vapor phase growth method, etc.
Alternatively, a sputtering method or the like may be used. The film thickness of the first semiconductor film 606a is 10 nm or more 5
It is preferably formed so as to be 0 nm or less.

The second semiconductor film 606b is an i-type semiconductor film (intrinsic semiconductor film) and is formed of an amorphous silicon film. To form the second semiconductor film 606b, an amorphous silicon film is formed by a plasma CVD method using a semiconductor material gas. Silane (SiH ₄ ) may be used as the semiconductor material gas. Alternatively, Si ₂ H ₆ , SiH ₂ Cl ₂ , SiHCl ₃ , S
iCl ₄ , SiF _{4, and the} like may be used. The formation of the second semiconductor film 606b is performed by the LPCVD method.
It may be carried out by a vapor phase growth method, a sputtering method or the like. The thickness of the second semiconductor film 606b is 2.
It is preferably formed so as to be 00 nm or more and 1000 nm or less.

The third semiconductor film 606c is an n-type semiconductor film, and is formed of an amorphous silicon film containing an impurity element that imparts the n-type. The third semiconductor film 606c is formed by a plasma CVD method using a semiconductor material gas containing an impurity element of Group 15 (for example, phosphorus (P)). Silane (SiH ₄ ) may be used as the semiconductor material gas. Or Si ₂ H ₆ ,
SiH ₂ Cl ₂ , SiHCl ₃ , SiC ₄ , SiF _{4, and the} like may be used. Further, after forming an amorphous silicon film containing no impurity element, the impurity element may be introduced into the amorphous silicon film by using a diffusion method or an ion implantation method. It is preferable to diffuse the impurity element by heating or the like after introducing the impurity element by an ion implantation method or the like. In this case, as a method for forming the amorphous silicon film, an LPCVD method, a vapor phase growth method, a sputtering method, or the like may be used. The thickness of the third semiconductor film 606c is preferably formed to be 20 nm or more and 200 nm or less.

Further, the first semiconductor film 606a, the second semiconductor film 606b, and the third semiconductor film 606c may be formed by using a polycrystalline semiconductor instead of an amorphous semiconductor, or a microcrystal (Semi Amorphous Semiconductor: SAS)) It may be formed using a semiconductor.

Microcrystalline semiconductors belong to a metastable state between amorphous and single crystals, considering the Gibbs free energy. That is, it is a semiconductor having a third state that is stable in free energy, has short-range order, and has lattice distortion. Columnar or acicular crystals grow in the normal direction with respect to the substrate surface. Microcrystalline silicon, which is a typical example of microcrystalline semiconductor, has its Raman spectrum shifted to a lower wavenumber side than 520 cm ^-1, which indicates single crystal silicon.
That is, 520 cm ^-1 indicating monocrystalline silicon and 480 cm ⁻ indicating amorphous silicon.
There is a peak in the Raman spectrum of microcrystalline silicon between ¹ . In addition, at least 1 atomic% or more of hydrogen or halogen is contained to terminate the unbonded hand (dangling bond). Further, by adding rare gas elements such as helium, argon, krypton, and neon to further promote the lattice strain, stability is increased and a good polycrystalline semiconductor film can be obtained.

This microcrystalline semiconductor film can be formed by a high-frequency plasma CVD method having a frequency of several tens of MHz to several hundreds of MHz, or a microwave plasma CVD apparatus having a frequency of 1 GHz or more. Typically, SiH ₄ , Si ₂ H ₆ , SiH ₂ Cl ₂ , SiHCl ₃ , SiCl ₄ , S.
The silicon hydride such as iF ₄ can be formed by dilution with hydrogen. Further, in addition to silicon hydride and hydrogen, it can be diluted with one or more rare gas elements selected from helium, argon, krypton, and neon to form a microcrystalline semiconductor film. At these times, the flow rate ratio of hydrogen to silicon hydride is 5 times or more and 200 times or less, preferably 50 times or more and 150 times or less.
More preferably, it is 100 times. Furthermore, in the gas containing silicon, CH ₄ , C ₂ H ₆
Carbide gas _etc., GeH 4, GeF _4, etc. germanium gas may be mixed with _{F 2} or the like.

Further, since the mobility of holes generated by the photoelectric effect is smaller than that of electrons, the pin-type photodiode shows a characteristic that it is better to use the p-type semiconductor film side as the light receiving surface. Here, p
Photodiode 602 from the surface of the substrate 601 on which the in-type photodiode is formed
An example of converting the light 622 received by the light into an electric signal is shown. Further, since the light from the semiconductor film side having a conductive type opposite to that of the semiconductor film side as the light receiving surface becomes ambient light, it is preferable to use a conductive film having a light-shielding property for the electrode layer. Further, the n-type semiconductor film side can also be used as a light receiving surface.

As the insulating film 632, the interlayer insulating film 633, and the interlayer insulating film 634, an insulating material is used, and depending on the material, a sputtering method, a plasma CVD method, an SOG method, a spin coating, a dip, a spray coating, and a droplet ejection are performed. It can be formed by a method (inkjet method or the like), screen printing, offset printing, a doctor knife, a roll coater, a curtain coater, a knife coater, or the like.

In this embodiment, an aluminum oxide film is used as the insulating film 631. The insulating film 631 can be formed by a sputtering method or a plasma CVD method.

The aluminum oxide film provided as the insulating film 631 on the oxide semiconductor film has a high blocking effect (blocking effect) that does not allow the film to permeate both impurities such as hydrogen and water and oxygen.

Therefore, the aluminum oxide film is a variable factor of hydrogen during and after the production process.
It functions as a protective film that prevents impurities such as moisture from being mixed into the oxide semiconductor film and the release of oxygen, which is a main component material constituting the oxide semiconductor, from the oxide semiconductor film.

In the present embodiment, the transistor 640 has an oxide semiconductor film that is highly purified and suppresses the formation of oxygen deficiency. Further, the transistor 640 has a silicon oxide film as a gate insulating film. The oxide semiconductor film contained in the transistor 640 forms a region having more oxygen than the chemical quantitative composition ratio by oxygen doping treatment, and heat treatment after doping is performed on the oxide semiconductor film with an insulating film 631. Because it is performed with the aluminum oxide film provided as
It is possible to prevent oxygen from being released from the oxide semiconductor film by the heat treatment. Therefore, the obtained oxide semiconductor film can be a film containing a region in which the oxygen content is more than the stoichiometric ratio.

The oxide semiconductor film contained in the transistor 640 is a high-purity film that has been dehydrated or dehydrogenated by at least one of heat treatment after film formation of the oxide semiconductor film and heat treatment after oxygen doping treatment. Is. Therefore, by using the oxide semiconductor film for the transistor 640, it is possible to reduce the variation in the threshold voltage Vth of the transistor and the shift ΔVth of the threshold voltage due to oxygen deficiency.

The insulating film 632 includes a silicon oxide layer and a silicon nitride nitride layer as the inorganic insulating material.
It is possible to use an oxide insulating film such as an aluminum oxide layer or an aluminum nitride layer, a single layer or a laminate of a nitride insulating film such as a silicon nitride layer, a silicon nitride layer, an aluminum nitride layer, or an aluminum nitride layer. it can.

As the interlayer insulating films 633 and 634, an insulating film that functions as a flattening insulating film is preferable in order to reduce surface irregularities. As the interlayer insulating films 633 and 634, heat-resistant organic insulating materials such as polyimide, acrylic resin, benzocyclobutene resin, polyamide, and epoxy resin can be used. In addition to the above organic insulating material, a low dielectric constant material (low-k)
Material), siloxane-based resin, PSG (phosphorus glass), BPSG (limboron glass), or other single layer, or laminate can be used.

By detecting the light incident on the photodiode 602, the information of the object to be detected can be read. A light source such as a backlight can be used when reading the information of the object to be detected.

As described above, the transistor having an oxide semiconductor film which is highly purified and contains an excess of oxygen to compensate for the oxygen deficiency is electrically stable because the fluctuation of the electrical characteristics of the transistor is suppressed. Therefore, it is possible to provide a highly reliable semiconductor device by using the transistor.

This embodiment can be implemented in combination with the configurations described in the other embodiments as appropriate.

(Embodiment 5)
The transistors illustrated in the first or second embodiment can be suitably used for a semiconductor device having an integrated circuit in which a plurality of transistors are stacked. In the present embodiment, an example of a storage medium (memory element) is shown as an example of the semiconductor device.

In the present embodiment, a semiconductor device including a first transistor manufactured on a single crystal semiconductor substrate and a second transistor manufactured by using a semiconductor film above the first transistor via an insulating film is manufactured. ..

FIG. 7 is an example of the configuration of the semiconductor device. FIG. 7A shows a cross section of the semiconductor device in FIG. 7 (A).
B) shows the plane of the semiconductor device, respectively. Here, FIG. 7 (A) is C of FIG. 7 (B).
Corresponds to the cross section in 1-C2 and D1-D2. Further, FIG. 7C shows an example of a circuit diagram when the semiconductor device is used as a memory element.

The semiconductor device shown in FIGS. 7A and 7B has a transistor 140 using the first semiconductor material at the lower part and a transistor 162 using the second semiconductor material at the upper part. The transistor illustrated in the first or second embodiment can be suitably used for the transistor 162. In this embodiment, an example is shown in which a transistor having the same structure as the transistor 510 shown in the second embodiment is used as the transistor 162.

The transistor 140 to be laminated, the semiconductor material of the transistor 162, and the structure may be the same or different. In this embodiment, a transistor having a material and a structure suitable for a circuit of a storage medium (memory element) is used, respectively. The first semiconductor material is a semiconductor material other than an oxide semiconductor, and the second semiconductor material is a second semiconductor material. It is an oxide semiconductor. As the semiconductor material other than the oxide semiconductor, for example, silicon, germanium, silicon germanium, silicon carbide, gallium arsenide or the like can be used, and it is preferable to use a single crystal semiconductor. Alternatively, an organic semiconductor material or the like may be used. Transistors using such semiconductor materials are easy to operate at high speed. On the other hand, a transistor using an oxide semiconductor can hold a charge for a long time due to its characteristics.

The transistor 140 has a channel forming region 116 provided on a substrate 185 containing a semiconductor material (for example, silicon), an impurity region 120 provided so as to sandwich the channel forming region 116, and a metal compound region in contact with the impurity region 120. 124 and channel formation region 1
It has a gate insulating film 108 provided on the gate insulating film 16 and a gate electrode layer 110 provided on the gate insulating film 108.

As the substrate 185 containing the semiconductor material, a single crystal semiconductor substrate such as silicon or silicon carbide, a polycrystalline semiconductor substrate, a compound semiconductor substrate such as silicon germanium, an SOI substrate, or the like can be applied. In general, the "SOI substrate" refers to a substrate having a structure in which a silicon semiconductor film is provided on an insulating surface, but in the present specification and the like, a semiconductor film made of a material other than silicon is provided on the insulating surface. Also includes the board of the configuration. That is, the semiconductor film of the "SOI substrate" is not limited to the silicon semiconductor film. Further, the SOI substrate includes a structure in which a semiconductor film is provided on an insulating substrate such as a glass substrate via an insulating film.

As a method for producing an SOI substrate, an oxide layer is formed from the surface to a certain depth by injecting oxygen ions into a mirror-polished wafer and then heated at a high temperature, and defects generated in the surface layer are eliminated. A method, a method of cleaving a semiconductor substrate by utilizing the growth of microvoids formed by hydrogen ion irradiation by heat treatment, a method of forming a single crystal semiconductor film by crystal growth on an insulating surface, and the like can be used.

For example, ions are added from one surface of a single crystal semiconductor substrate to form a fragile layer from one surface of the single crystal semiconductor substrate to a certain depth, and the fragile layer is formed on one surface of the single crystal semiconductor substrate or an element. An insulating film is formed on either one of the substrates. In a state where the single crystal semiconductor substrate and the element substrate are overlapped with the insulating film sandwiched between them, a crack is generated in the fragile layer, and a heat treatment is performed to separate the single crystal semiconductor substrate by the fragile layer. A single crystal semiconductor film is formed on the device substrate as a film. The SOI substrate produced by the above method can also be preferably used.

An element separation insulating film 106 is provided on the substrate 185 so as to surround the transistor 140. In order to realize high integration, it is desirable that the transistor 140 does not have a sidewall insulating film as shown in FIG. 7A. On the other hand, transistor 14
When the characteristic of 0 is emphasized, a sidewall insulating film may be provided on the side surface of the gate electrode layer 110, and an impurity region 120 including a region having a different impurity concentration may be provided.

The transistor 140 using the single crystal semiconductor substrate is capable of high-speed operation. Therefore, by using the transistor as a reading transistor, information can be read at high speed.

In the present embodiment, two insulating films are formed so as to cover the transistor 140. However, the insulating film covering the transistor 140 may have a single-layer structure or a laminated structure of three or more layers. However, a silicon oxide film shall be applied as the insulating film in contact with the oxide semiconductor film contained in the transistor 162 provided on the upper part.

As a process before forming the transistor 162 and the capacitive element 164, CMP is applied to the two insulating film layers.
The treatment is applied to form a flattened insulating film 128 and an insulating film 130, and at the same time, the gate electrode layer 1
The upper surface of 10 is exposed.

The insulating film 128 and the insulating film 130 are typically such as a silicon oxide film, a silicon nitride film, an aluminum oxide film, an aluminum nitride film, a silicon nitride film, an aluminum nitride film, a silicon nitride film, and an aluminum nitride film. An inorganic insulating film can be used. The insulating film 128 and the insulating film 130 can be formed by using a plasma CVD method, a sputtering method, or the like.

In addition, organic materials such as polyimide, acrylic resin, and benzocyclobutene resin can be used. In addition to the above organic materials, low dielectric constant materials (low-k materials) and the like can be used. When an organic material is used, the insulating film 128 and the insulating film 130 may be formed by a wet method such as a spin coating method or a printing method.

In the present embodiment, a silicon oxide film having a film thickness of 50 nm is formed as the insulating film 128 by the sputtering method, and a silicon oxide film having a film thickness of 550 nm is formed as the insulating film 130 by the sputtering method.

Then, an oxide semiconductor film is formed on the insulating film 130 that has been sufficiently flattened by CMP treatment.
This is processed to form an island-shaped oxide semiconductor film 144. After forming the oxide semiconductor film,
It is preferable to perform heat treatment for dehydration or dehydrogenation.

Next, a conductive layer is formed on the gate electrode layer 110, the insulating film 128, the insulating film 130, etc., and the conductive layer is selectively etched to select the source electrode layer or the drain electrode layer 142a, the drain electrode layer or the source. The electrode layer 142b is formed.

The conductive layer is a PVD method such as a sputtering method, or a CVD method such as a plasma CVD method.
It can be formed using the method. Further, as the material of the conductive layer, Al, Cr, Cu, T
Elements selected from a, Ti, Mo, and W, alloys containing the above-mentioned elements as components, and the like can be used. Any one of Mn, Mg, Zr, Be, Nd, Sc, or a material obtained by combining a plurality of these may be used.

The conductive layer may have a single-layer structure or a laminated structure of two or more layers. For example, a single-layer structure of a titanium film or a titanium nitride film, a single-layer structure of an aluminum film containing silicon, a two-layer structure in which a titanium film is laminated on an aluminum film, and a two-layer structure in which a titanium film is laminated on a titanium nitride film. Examples thereof include a structure, a three-layer structure in which a titanium film, an aluminum film, and a titanium film are laminated. When the conductive layer has a single layer structure of a titanium film or a titanium nitride film, it is easy to process the source electrode layer or drain electrode layer 142a having a tapered shape and the drain electrode layer or source electrode layer 142b. There is a merit that there is.

The channel length (L) of the upper transistor 162 is the source electrode layer or the drain electrode layer 1.
It is determined by the distance between the 42a and the lower end of the drain electrode layer or the source electrode layer 142b. When the mask forming exposure used when forming a transistor having a channel length (L) of less than 25 nm is performed, it is desirable to use ultraviolet rays having a short wavelength of several nm to several tens of nm.

Next, the gate insulating film 146 in contact with a part of the oxide semiconductor film 144 is formed. As the gate insulating film 146, a silicon oxide film can be obtained by using a plasma CVD method, a sputtering method, or the like.
A silicon nitride film, a silicon oxide film, a silicon nitride film, a hafnium oxide film, or the like can be formed.

After the gate insulating film 146 is formed, oxygen doping treatment is performed to form an oxygen excess region in the oxide semiconductor film 144.

Next, the gate electrode layer 148a is formed on the gate insulating film 146 in the region overlapping with the oxide semiconductor film 144, and the electrode layer 148b is formed in the region overlapping with the source electrode layer or the drain electrode layer 142a.

The gate electrode layer 148a and the electrode layer 148b can be formed by forming a conductive layer on the gate insulating film 146 and then selectively etching the conductive layer.

Next, an insulating film 150 including an aluminum oxide film is formed on the gate insulating film 146, the gate electrode layer 148a, and the electrode layer 148b. When the insulating film 150 has a laminated structure, a silicon oxide film, a silicon nitride film, a silicon nitride film, a silicon nitride film, an aluminum nitride film, an aluminum nitride film, etc. are used by a plasma CVD method, a sputtering method, or the like.
An aluminum oxide film, a hafnium oxide film, or a gallium oxide film may be laminated with an aluminum oxide film.

After forming the insulating film 150, a heat treatment (preferably a second heat treatment) is performed. The temperature of the heat treatment is preferably 350 ° C. or higher and 650 ° C. or lower, more preferably 450 ° C. or higher and 650 ° C. or lower, or lower than the strain point of the substrate. The timing of the oxygen doping treatment and the heat treatment after the oxygen doping treatment (second heat treatment) is not limited to the configuration of the present embodiment, but the heat treatment is performed at least by the insulating film 150 (more specifically, aluminum oxide). It is necessary to perform after the film formation of the film). The aluminum oxide film used as the insulating film 150 has a high blocking effect (blocking effect) that does not allow the film to permeate both impurities such as hydrogen and moisture, and oxygen. By performing heat treatment after the insulating film 150 is formed. This is because the release of oxygen from the oxide semiconductor film 144 can be prevented.

Next, the insulating film 152 is formed on the transistor 162 and the insulating film 150. Insulating film 15
2 can be formed by using a sputtering method, a CVD method, or the like. Further, it can be formed by using a material containing an inorganic insulating material such as silicon oxide, silicon oxide nitride, silicon nitride, hafnium oxide, and aluminum oxide.

Next, openings are formed in the gate insulating film 146, the insulating film 150, and the insulating film 152 to reach the drain electrode layer or the source electrode layer 142b. The opening is formed by selective etching using a mask or the like.

After that, the wiring 156 in contact with the drain electrode layer or the source electrode layer 142b is formed in the opening. In addition, in FIG. 7A, the drain electrode layer or the source electrode layer 142b and the wiring 156 are shown.
The connection point with is not shown.

The wiring 156 is C such as a PVD method including a sputtering method and a plasma CVD method.
It is formed by forming a conductive layer using the VD method and then etching the conductive layer. Further, as the material of the conductive layer, an element selected from Al, Cr, Cu, Ta, Ti, Mo, and W, an alloy containing the above-mentioned element as a component, and the like can be used. Mn, Mg, Z
Any one of r, Be, Nd, Sc, or a material obtained by combining a plurality of these may be used. The details are the same as those of the source electrode layer, the drain electrode layer 142a, and the like.

The transistor 162 and the capacitive element 164 are completed by the above steps. The transistor 162 is a transistor having an oxide semiconductor film 144 that is highly purified and contains an excess of oxygen to compensate for oxygen deficiency. Therefore, the transistor 162 is electrically stable because the fluctuation of the electrical characteristics is suppressed. The capacitive element 164 includes a source electrode layer or a drain electrode layer 142a, a gate insulating film 146, and an electrode layer 148b.

In the capacitive element 164 of FIG. 7, the gate insulating film 146 can sufficiently secure the insulating property between the source electrode layer or the drain electrode layer 142a and the electrode layer 148b.
Of course, in order to secure a sufficient capacity, a capacitance element 164 having a configuration further having an insulating film may be adopted. Further, when the capacitance is not required, it is possible to configure the configuration without the capacitance element 164.

FIG. 7C shows an example of a circuit diagram when the semiconductor device is used as a memory element.
In FIG. 7C, one of the source electrode layer or the drain electrode layer of the transistor 162, one of the electrode layers of the capacitive element 164, and the gate electrode layer of the transistor 140 are electrically connected. Further, the first wiring (also called 1st line: source wire) and the source electrode layer of the transistor 140 are electrically connected, and the second wiring (2nd line: also called bit wire) and the drain electrode of the transistor 140 are electrically connected. The layers are electrically connected. In addition, the third wiring (3rd Line: also called the first signal line) and the transistor 162
Is electrically connected to the other of the source electrode layer and the drain electrode layer of the fourth wiring (4t).
h Line: also called a second signal line) and the gate electrode layer of the transistor 162 are electrically connected. The fifth wiring (also called a 5th line) and the other of the electrode layer of the capacitive element 164 are electrically connected.

Since the transistor 162 using an oxide semiconductor has a feature that the off current is extremely small, by turning the transistor 162 into an off state, one of the source electrode layer and the drain electrode layer of the transistor 162 and a capacitive element It is possible to maintain the potential of a node (hereinafter, node FG) in which one of the electrode layers of 164 and the gate electrode layer of the transistor 140 are electrically connected for an extremely long time. Then, by having the capacitance element 164, it becomes easy to hold the electric charge given to the node FG, and it becomes easy to read the held information.

When storing (writing) information in the semiconductor device, first, the potential of the fourth wiring is set to the potential at which the transistor 162 is turned on, and the transistor 162 is turned on. As a result, the potential of the third wiring is supplied to the node FG, and a predetermined amount of electric charge is accumulated in the node FG. Here, it is assumed that one of charges giving two different potential levels (hereinafter, referred to as low level charge and high level charge) is given. After that, the potential of the fourth wiring is set to the potential at which the transistor 162 is turned off, and the transistor 162 is turned off, so that the node FG is in a floating state, so that a predetermined charge is held in the node FG. It will be in the same state. As described above, by causing the node FG to accumulate and retain a predetermined amount of electric charge, information can be stored in the memory cell.

Since the off-current of the transistor 162 is extremely small, the charge supplied to the node FG is retained for a long time. Therefore, the refresh operation becomes unnecessary, or the frequency of the refresh operation can be made extremely low, and the power consumption can be sufficiently reduced. Further, even when there is no power supply, it is possible to retain the stored contents for a long period of time.

When reading the stored information (reading), if a predetermined potential (constant potential) is given to the first wiring and an appropriate potential (reading potential) is given to the fifth wiring, the node FG holds the information. The transistor 140 takes a different state depending on the amount of electric charge applied. Generally, transistor 1
Assuming that 40 is an n-channel type, the apparent threshold value _{Vth_H} of the transistor 140 when the high level charge is held in the node FG is the apparent threshold value V _{th_H} of the transistor 140 when the low level charge is held in the node FG. This is because it is lower than the threshold value V _{th_L of} . Here, the apparent threshold value means the potential of the fifth wiring required to put the transistor 140 in the "on state". Therefore, the potential of the fifth wiring is set to _{Vth.
By setting} the potential V ₀ between _{_H} and V _{th_L} , the charge held in the node FG can be discriminated. For example, in writing, when a high level charge is given,
When the potential of the fifth wiring becomes V ₀ (> V _{th_H} ), the transistor 140 is “on state”.
Will be. When the Low level charge is given, the potential of the fifth wiring is V ₀ (<V _{t).
Even when h_L} ) is set, the transistor 140 remains in the “off state”. Therefore, the fifth
The stored information can be read out by controlling the potential of the wiring of the transistor 140 and reading out the on state or the off state of the transistor 140 (reading out the potential of the second wiring).

Further, when rewriting the stored information, the node FG is made to hold the electric charge related to the new information by supplying a new potential to the node FG holding a predetermined amount of electric charge by the above writing. Specifically, the potential of the fourth wiring is set to the potential at which the transistor 162 is turned on, and the transistor 162 is turned on. As a result, the potential of the third wiring (potential related to new information) is supplied to the node FG, and a predetermined amount of electric charge is accumulated in the node FG. After that, the potential of the fourth wiring is set to the potential at which the transistor 162 is turned off, and the transistor 162 is turned off, so that the node FG is in a state where the electric charge related to the new information is held. That is, it is possible to overwrite the stored information by performing the same operation (second writing) as the first writing while the node FG holds a predetermined amount of electric charge by the first writing. Is.

The transistor 162 shown in the present embodiment is highly purified, and by using an oxide semiconductor film containing an excess of oxygen for the oxide semiconductor film 144, the off-current of the transistor 162 can be sufficiently reduced. Then, by using such a transistor, a semiconductor device capable of retaining the stored contents for an extremely long period of time can be obtained.

As described above, the transistor having an oxide semiconductor film which is highly purified and contains an excess of oxygen to compensate for the oxygen deficiency is electrically stable because the fluctuation of electrical characteristics is suppressed. Therefore, it is possible to provide a highly reliable semiconductor device by using the transistor.

As described above, the configurations and methods shown in the present embodiment can be appropriately combined with the configurations and methods shown in other embodiments.

(Embodiment 6)
The semiconductor device disclosed in the present specification can be applied to various electronic devices (including game machines). Examples of electronic devices include television devices (also referred to as televisions or television receivers), monitors for computers, digital cameras, cameras such as digital video cameras, digital photo frames, and mobile phones (mobile phones, mobile phones). (Also referred to as a device), a portable game machine, a mobile information terminal, a sound reproduction device, a large game machine such as a pachinko machine, and the like. An example of an electronic device including the semiconductor device described in the above embodiment will be described.

FIG. 13A shows a notebook-type personal computer, which has a main body 3001 and a housing 300.
2. It is composed of a display unit 3003, a keyboard 3004, and the like. By applying the semiconductor device shown in any of the above embodiments to the display unit 3003, a highly reliable notebook-type personal computer can be obtained.

FIG. 13B shows a personal digital assistant (PDA), which has a display unit 3023 and a display unit 3023 on the main body 3021.
An external interface 3025, an operation button 3024, and the like are provided. There is also a stylus 3022 as an accessory for operation. By applying the semiconductor device shown in any of the above embodiments to the display unit 3023, a more reliable personal digital assistant (PDA) can be obtained.

FIG. 13C shows an example of an electronic book. For example, an electronic book is composed of two housings, a housing 2701 and a housing 2703. The housing 2701 and the housing 2703 are integrated by a shaft portion 2711, and the opening / closing operation can be performed with the shaft portion 2711 as an axis. With such a configuration, it is possible to perform an operation like a paper book.

A display unit 2705 is incorporated in the housing 2701, and a display unit 2707 is incorporated in the housing 2703. The display unit 2705 and the display unit 2707 may be configured to display a continuous screen or may be configured to display different screens. By displaying different screens, for example, a sentence is displayed on the right display unit (display unit 2705 in FIG. 13 (C)), and an image is displayed on the left display unit (display unit 2707 in FIG. 13 (C)). Can be displayed. By applying the semiconductor device shown in any of the above embodiments to the display unit 2705 and the display unit 2707, a highly reliable electronic book can be obtained. When a transflective or reflective liquid crystal display device is used as the display unit 2705, it is expected to be used in relatively bright conditions. Therefore, a solar cell can be provided to generate electricity by the solar cell and charge the battery. You may do so. If a lithium ion battery is used as the battery, there is an advantage that the size can be reduced.

Further, FIG. 13C shows an example in which the housing 2701 is provided with an operation unit or the like. For example
The housing 2701 includes a power supply 2721, operation keys 2723, a speaker 2725, and the like. The page can be fed by the operation key 2723. A keyboard, a pointing device, or the like may be provided on the same surface as the display unit of the housing. Further, the back surface or the side surface of the housing may be provided with an external connection terminal (earphone terminal, USB terminal, etc.), a recording medium insertion portion, or the like. Further, the electronic book may be configured to have a function as an electronic dictionary.

Further, the electronic book may be configured so that information can be transmitted and received wirelessly. It is also possible to purchase desired book data or the like from an electronic book server and download it wirelessly.

FIG. 13 (D) is a mobile phone, which is composed of two housings, a housing 2800 and a housing 2801. The housing 2801 includes a display panel 2802, a speaker 2803, a microphone 2804, a pointing device 2806, a camera lens 2807, an external connection terminal 2808, and the like. Further, the housing 2800 is provided with a solar cell 2810 for charging a mobile phone, an external memory slot 2811, and the like. The antenna is a housing 28.
It is built in 01. By applying the semiconductor device shown in any of the above embodiments to the display panel 2802, a highly reliable mobile phone can be obtained.

Further, the display panel 2802 is provided with a touch panel, and in FIG. 13D, a plurality of operation keys 2805 displayed as images are shown by dotted lines. A booster circuit for boosting the voltage output by the solar cell 2810 to a voltage required for each circuit is also mounted.

The display direction of the display panel 2802 changes as appropriate according to the usage pattern. Further, since the camera lens 2807 is provided on the same surface as the display panel 2802, a videophone can be made. Speaker 2803 and microphone 2804 are not limited to voice calls, but videophones,
Recording and playback are possible. Further, the housing 2800 and the housing 2801 can be slid and changed from the unfolded state as shown in FIG. 13D to the overlapping state, and can be miniaturized suitable for carrying.

The external connection terminal 2808 can be connected to various cables such as an AC adapter and a USB cable, and can be charged and data communication with a personal computer or the like is possible. Further, a recording medium can be inserted into the external memory slot 2811 to support storage and movement of a larger amount of data.

Further, in addition to the above functions, an infrared communication function, a television reception function, and the like may be provided.

FIG. 13 (E) is a digital video camera, the main body 3051, the display unit (A) 3057,
It is composed of an eyepiece 3053, an operation switch 3054, a display (B) 3055, a battery 3056, and the like. The semiconductor device shown in any of the above embodiments is displayed on the display unit (A).
) 3057, the display unit (B) 3055 can be applied to a highly reliable digital video camera.

FIG. 13F shows an example of a television device. The television device has a housing 96.
A display unit 9603 is incorporated in 01. The display unit 9603 makes it possible to display an image. Further, here, a configuration in which the housing 9601 is supported by the stand 9605 is shown. By applying the semiconductor device shown in any of the above embodiments to the display unit 9603, a highly reliable television device can be obtained.

The operation of the television device can be performed by the operation switch provided in the housing 9601 or a separate remote control operation device. Further, the remote controller operating device may be provided with a display unit for displaying information output from the remote controller operating device.

The television device is configured to include a receiver, a modem, and the like. The receiver can receive general television broadcasts, and by connecting to a wired or wireless communication network via a modem, it can be unidirectional (sender to receiver) or bidirectional (sender and receiver). It is also possible to perform information communication between (or between recipients, etc.).

This embodiment can be implemented in combination with the configurations described in the other embodiments as appropriate.

In this example, the characteristics of the aluminum oxide film used in the semiconductor device according to the disclosed invention as a barrier film were evaluated. The results are shown in FIGS. 14 to 17. As an evaluation method, secondary ion mass spectrometry (SIMS: Secondary Ion Mass Sp.)
spectrum) and TDS (Thermal Deservation Spec)
tromy: warm-up desorption gas spectroscopy) analysis method was used.

First, the evaluation performed by SIMS analysis is shown. The samples are Comparative Example Sample A in which a silicon oxide film having a film thickness of 100 nm was formed on a glass substrate by a sputtering method as a comparative example, and Comparative Example Sample A in which a silicon oxide film having a film thickness of 100 nm was formed on a glass substrate by a sputtering method as an example. Example Sample A in which an aluminum oxide film having a film thickness of 100 nm was formed on a silicon film by a sputtering method was prepared.

In Comparative Example Sample A and Example Sample A, the film forming condition of the silicon oxide film is that a silicon oxide (SiO ₂ ) target is used as a target and the distance between the glass substrate and the target is 60.
mm, pressure 0.4 Pa, power supply power 1.5 kW, oxygen (oxygen flow rate 50 sccm) atmosphere,
The substrate temperature was 100 ° C.

In Example Sample A, the film forming condition of the aluminum oxide film was that an aluminum oxide (Al ₂ O ₃ ) target was used as the target and the distance between the glass substrate and the target was 60 mm.
Pressure 0.4 Pa, power supply power 1.5 kW, argon and oxygen (argon flow rate 25 sccm:
The substrate temperature was 250 ° C. under an atmosphere (oxygen flow rate 25 sccm).

Pressure Cooker Test (PCT: Pressure) on Comparative Example Sample A and Example Sample A
Cooker Test) was performed. In this example, as a PCT test, the temperature is 130 ° C.
Humidity 85%, H ₂ O (water): D ₂ O (heavy water) = 3: 1 atmosphere, 2.3 atm (0.23 MP)
Comparative Example sample A and Example sample A were held for 100 hours under the condition of a).

SSDP (Substrate Side Depth Profile) as a SIMS analysis
le) -SIMS was used to measure the concentrations of H and D atoms in each of Comparative Example Sample A and Example Sample A before and after the PCT test.

14 (A1) shows the PCT of Comparative Example Sample A before the PCT test, and FIG. 14 (A2) shows the PCT of Comparative Example Sample A.
The concentration profiles of H and D atoms by SIMS after the test are shown. In FIGS. 14 (A1) and 14 (A2), the D atom exposed profile is a concentration profile of D atoms existing in nature calculated from the profile of H atoms assuming that the abundance ratio of D atoms is 0.015%. Therefore, the amount of D atom mixed in the sample by the PCT test is the measured D.
It is the difference between the atomic concentration and the D atom extracted concentration. From the measured D atom concentration, D atom e
The concentration profile of the D atom after subtracting the extracted concentration is shown in FIG. 14 before the PCT test.
B1) and after the PCT test are shown in FIG. 14 (B2).

Similarly, FIG. 15 (A1) shows the example sample A before the PCT test, and FIG. 15 (A2) shows the example sample A.
The concentration profile of H atom and D atom by SIMS after the PCT test of is shown. Further, the concentration profile of the D atom obtained by subtracting the D atom extracted concentration from the actually measured D atom concentration is shown in FIG. 15 (B1) before the PCT test and in FIG. 15 (B2) after the PCT test.

The SIMS analysis results of this example are all quantified using a standard sample of silicon oxide film.

As shown in FIG. 14, the measured D atom concentration profile and D that overlapped before the PCT test
As for the atomic exposed profile, after the PCT test, the actually measured concentration profile of D atoms increased to a high concentration, indicating that D atoms were mixed in the silicon oxide film. Therefore,
It was confirmed that the silicon oxide film of the comparative example sample had a low barrier property against moisture (H ₂ O, D ₂ O) from the outside.

On the other hand, as shown in FIG. 15, in Example Sample A in which the aluminum oxide film was laminated on the silicon oxide film, even after the PCT test, only a slight intrusion of D atoms was observed in the region near the surface of the aluminum oxide film, and the sample A was oxidized. No invasion of D atoms is observed after the aluminum film depth is around 30 nm and in the silicon oxide film. Therefore, the aluminum oxide film has external moisture (H ₂ O, D ₂ O).
On the other hand, it was confirmed that the barrier property was high.

Next, the evaluation performed by TDS analysis is shown. As an example, Example Sample B in which a silicon oxide film having a film thickness of 100 nm was formed on a glass substrate by a sputtering method and an aluminum oxide film having a film thickness of 20 nm was formed on a silicon oxide film by a sputtering method was prepared. Further, as a comparative example, after measuring Example Sample B by TDS analysis, the aluminum oxide film was removed from Example Sample B to prepare Comparative Example Sample B in which only the silicon oxide film was formed on the glass substrate.

In Comparative Example Sample B and Example Sample B, the film forming condition of the silicon oxide film is that a silicon oxide (SiO ₂ ) target is used as a target and the distance between the glass substrate and the target is 60.
mm, pressure 0.4 Pa, power supply power 1.5 kW, oxygen (oxygen flow rate 50 sccm) atmosphere,
The substrate temperature was 100 ° C.

In Example Sample B, the film forming condition of the aluminum oxide film was that an aluminum oxide (Al ₂ O ₃ ) target was used as the target and the distance between the glass substrate and the target was 60 mm.
Pressure 0.4 Pa, power supply power 1.5 kW, argon and oxygen (argon flow rate 25 sccm:
The substrate temperature was 250 ° C. under an atmosphere (oxygen flow rate 25 sccm).

In Comparative Example Sample B and Example Sample B, further 300 ° C. heat treatment, 450 ° C. heat treatment,
Samples were prepared by treating for 1 hour in a nitrogen atmosphere under the conditions of heat treatment at 600 ° C.

In Comparative Example Sample B and Example Sample B, TDS analysis was performed on samples prepared under four conditions: no heat treatment, 300 ° C. heat treatment, 450 ° C. heat treatment, and 600 ° C. heat treatment. In Comparative Example Sample B and Example Sample B, FIGS. 16 (A) and 17 (A) were not heat-treated, and FIGS. 16 (B) and 17 (B) were heat-treated at 300 ° C., FIGS. 16 (C) and 17 (C). FIG. 17 (C)
16 (D) and 17 (D) show the measured TDS results of M / z = 32 (O ₂ ) of each sample subjected to the heat treatment at 450 ° C. and the heat treatment at 600 ° C.

As shown in FIGS. 16A to 16D, in Comparative Example Sample B, oxygen was released from the silicon oxide film in FIG. 16A without heat treatment, but it was heated at 300 ° C. in FIG. 16B. The amount of oxygen released was greatly reduced in the treated sample, and in the sample subjected to the 450 ° C. heat treatment in FIG. 16 (C) and the sample subjected to the 600 ° C. heat treatment in FIG. 16 (D), the TDS measurement was performed. It was below the background.

From the results of FIGS. 16A to 16D, 90% or more of the excess oxygen contained in the silicon oxide film is released from the silicon oxide film to the outside by heat treatment at 300 ° C., and 450 ° C. and 600 ° C.
It can be seen that excess oxygen contained in almost all silicon oxide films was released to the outside of the silicon oxide film by the heat treatment of. Therefore, it was confirmed that the silicon oxide film has a low barrier property against oxygen.

On the other hand, as shown in FIGS. 17A to 17D, in Example sample B in which the aluminum oxide film was formed on the silicon oxide film, the sample subjected to the heat treatment at 300 ° C., 450 ° C., and 600 ° C. Also, the same amount of oxygen was released as the sample without heat treatment.

From the results of FIGS. 17A to 17D, by forming the aluminum oxide film on the silicon oxide film, excess oxygen contained in the silicon oxide film is not easily released to the outside even if heat treatment is performed. , It can be seen that the state contained in the silicon oxide film is maintained to a considerable extent. Therefore, it was confirmed that the aluminum oxide film has a high barrier property against oxygen.

From the above results, it was confirmed that the aluminum oxide film has both a barrier property against hydrogen and water and a barrier property against oxygen, and functions suitably as a barrier film against hydrogen, water and oxygen.

Therefore, the aluminum oxide film is mainly composed of impurities such as hydrogen and water, which are variable factors, mixed into the oxide semiconductor film during and after the production process of the transistor containing the oxide semiconductor film, and constitutes the oxide semiconductor. It can function as a protective film that prevents the release of oxygen, which is a component material, from the oxide semiconductor film.

Further, the oxide semiconductor film to be formed has high purity because impurities such as hydrogen and water are not mixed in, and oxygen release is prevented. Therefore, the composition ratio of oxygen is relative to the stoichiometric composition ratio of the oxide semiconductor. Includes regions with excessive content. Therefore, by using the oxide semiconductor film for the transistor, it is possible to reduce the variation in the threshold voltage Vth of the transistor and the shift ΔVth of the threshold voltage due to oxygen deficiency.

106 Element separation insulating film 108 Gate insulating film 110 Gate electrode layer 116 Channel forming region 120 Impurity region 124 Metal compound region 128 Insulating film 130 Insulating film 140 Transistor 142a Drain electrode layer 142b Source electrode layer 144 Oxide semiconductor film 146 Gate insulating film 148a Gate electrode layer 148b Electrode layer 150 Insulation film 152 Insulation film 162 Transistor 164 Capacitive element 185 Substrate 400 Substrate 401 Gate electrode layer 402 Gate insulating film 403 Oxide semiconductor film 405a Source electrode layer 405b Drain electrode layer 407 Insulation film 410 Transistor 420 Transistor 421 Oxygen 502 Gate insulating film 506 Underlayer insulating film 510 Transistor 520 Transistor 601 Substrate 602 Photo diode 606a Semiconductor film 606b Semiconductor film 606c Semiconductor film 608 Adhesive layer 613 Substrate 631 Insulating film 632 Insulating film 633 Interlayer insulating film 634 Interlayer insulating film 640 Transistor 641a Electrode Layer 641b Electrode layer 642 Electrode layer 643 Conductive layer 645 Gate electrode layer 656 Transistor 658 Photodioden reset signal line 659 Gate signal line 671 Photosensor output signal line 672 Photosensor reference signal line 2701 Housing 2703 Housing 2705 Display 2707 Display 2711 Shaft 2721 Power supply 2723 Operation key 2725 Speaker 2800 Housing 2801 Housing 2802 Display panel 2803 Speaker 2804 Microphone 2805 Operation key 2806 Pointing device 2807 Camera lens 2808 External connection terminal 2810 Solar cell 2811 External memory slot 3001 Main unit 3002 3003 Display unit 3004 Keyboard 3021 Main unit 3022 Stylus 3023 Display unit 3024 Operation button 3025 External interface 3051 Main unit 3053 Eyepiece 3054 Operation switch 3056 Battery 4001 Board 4002 Pixel unit 4003 Signal line drive circuit 4004 Scanning line drive circuit 4005 Seal material 4006 Board 4008 Liquid crystal layer 4010 Transistor 4011 Transistor 4013 Liquid crystal element 4015 Connection terminal electrode layer 4016 Terminal electrode layer 4018 FPC
4019 Anisotropic conductive film 4020 Insulating film 4021 Insulating film 4023 Insulating film 4024 Insulating film 4030 Electrode layer 4031 Electrode layer 4032 Insulating film 4033 Insulating film 4510 Partition 4511 Electroluminescent layer 4513 Light emitting element 4514 Filling material 4612 Cavity 4613 Spherical particle 4614 Filling material 4615a Black area 4615b White area 9601 Housing 9603 Display 9605 Stand

Claims (1)

The process of forming a silicon oxide film and
The step of forming an oxide semiconductor film in contact with the silicon oxide film and
The step of forming an aluminum oxide film on the oxide semiconductor film and
A step of performing oxygen doping treatment on the oxide semiconductor film and supplying oxygen to the oxide semiconductor film to form a region having more oxygen than the stoichiometric composition ratio in the oxide semiconductor film.
A method for manufacturing a semiconductor device, comprising a step of heat-treating the oxide semiconductor film and the aluminum oxide film to which oxygen has been supplied.

Images